The reverberations of the two explosions that rocked the Boston marathon, leaving three dead and more than 140 wounded, has placed many major cities on high alert.
French police patrol on April 16, 2013 on the Trocadero plazza in front of the Eiffel Tower in Paris. France on April 16 ordered police patrols to be stepped up after at least two people were killed and 23 others wounded in two explosions on April 15 near the finish line of the Boston Marathon. AFP PHOTO / FRED DUFOURFRED DUFOUR/AFP/Getty Images
French police patrol on April 16, 2013 on the Trocadero plazza in front of the Eiffel Tower in Paris. France on April 16 ordered police patrols to be stepped up after at least two people were killed and 23 others wounded in two explosions on April 15 near the finish line of the Boston Marathon. AFP PHOTO / FRED DUFOURFRED DUFOUR/AFP/Getty Images
Amtrak police officers and their dogs watch as commuters walk through Penn Station, Tuesday, April 16, 2013 in New York. The deadly explosions at the Boston Marathon on Monday reverberated on both sides of the Atlantic as cities from Los Angeles to London saw a surge in security. (AP Photo/Mark Lennihan)
A solitary runner heads down the banks of the Charles River in Cambridge, Mass., in front of the Boston skyline, at dawn the morning after explosions killed three and injured more than 140 at the Boston Marathon, Tuesday, April 16, 2013. The bombs that blew up seconds apart at the finish line of one of the world’s most storied races left the streets spattered with blood and glass, and gaping questions of who chose to attack at the Boston Marathon and why. (AP Photo/Charles Krupa)
Swat team members and special police units assemble in the Boston Common on April 16, 2013 in Boston, Massachusetts. Security is especially tight in the city of Boston after two explosions went off near the finish of the Marathon, killing three people and injuring at least 141 others. (Photo by Darren McCollester/Getty Images)
German and United States security officers patrol in front of the U.S. embassy in Berlin, Tuesday, April 16, 2013. On Monday April 15, 2013 two bombs exploded in the crowded streets near the finish line of the Boston marathon. (AP Photo/Markus Schreiber)
French soldiers patrol on April 16, 2013 in front of the Eiffel Tower in Paris. France on April 16 ordered police patrols to be stepped up after at least two people were killed and 23 others wounded in two explosions on April 15 near the finish line of the Boston Marathon. AFP PHOTO / FRED DUFOURFRED DUFOUR/AFP/Getty Images
French soldiers patrol on April 16, 2013 in front of the Eiffel Tower in Paris. France on April 16 ordered police patrols to be stepped up after at least two people were killed and 23 others wounded in two explosions on April 15 near the finish line of the Boston Marathon. AFP PHOTO / FRED DUFOURFRED DUFOUR/AFP/Getty Images
French soldiers patrol on April 16, 2013 in front of the Eiffel Tower in Paris. France on April 16 ordered police patrols to be stepped up after at least two people were killed and 23 others wounded in two explosions on April 15 near the finish line of the Boston Marathon. AFP PHOTO / FRED DUFOURFRED DUFOUR/AFP/Getty Images
French soldiers patrol on April 16, 2013 in front of the Eiffel Tower in Paris. France on April 16 ordered police patrols to be stepped up after at least two people were killed and 23 others wounded in two explosions on April 15 near the finish line of the Boston Marathon. AFP PHOTO / FRED DUFOURFRED DUFOUR/AFP/Getty Images
A man walks through security barriers put up outside St Paul’s Cathedral in London, Tuesday, April 16, 2013. British police are reviewing security plans for Sunday’s London Marathon, the next major international marathon, because of the bombs that killed three people at the race in Boston. Police already were preparing a major security operation for Wednesday’s ceremonial funeral for former Prime Minister Margaret Thatcher, an event at St. Paul’s Cathedral that will be attended by Queen Elizabeth II and many dignitaries. The funeral’s security plans are expected to be reviewed in light of the Boston bombings. (AP Photo/Matt Dunham)
A woman walks through security barriers put up outside St Paul’s Cathedral in London, Tuesday, April 16, 2013. British police are reviewing security plans for Sunday’s London Marathon, the next major international marathon, because of the bombs that killed three people at the race in Boston. Police already were preparing a major security operation for Wednesday’s ceremonial funeral for former Prime Minister Margaret Thatcher, an event at St. Paul’s Cathedral that will be attended by Queen Elizabeth II and many dignitaries. The funeral’s security plans are expected to be reviewed in light of the Boston bombings. (AP Photo/Matt Dunham)
City of London police officers stand outside St Paul’s Cathedral in London, Tuesday, April 16, 2013. British police are reviewing security plans for Sunday’s London Marathon, the next major international marathon, because of the bombs that killed three people at the race in Boston. Police already were preparing a major security operation for Wednesday’s ceremonial funeral for former Prime Minister Margaret Thatcher, an event at St. Paul’s Cathedral that will be attended by Queen Elizabeth II and many dignitaries. The funeral’s security plans are expected to be reviewed in light of the Boston bombings. (AP Photo/Matt Dunham)
A piece of debris rests against a police barricade near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. Three people are confirmed dead and at least 141 injured after the explosions went off near the finish line of the marathon yesterday. The bombings at the 116-year-old Boston race, resulted in heightened security across the nation with cancellations of many professional sporting events as authorities search for a motive to the violence. (Photo by Spencer Platt/Getty Images)
National Guard soldiers stand near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. Three people are confirmed dead and at least 141 injured after the explosions went off near the finish line of the marathon yesterday. The bombings at the 116-year-old Boston race, resulted in heightened security across the nation with cancellations of many professional sporting events as authorities search for a motive to the violence. (Photo by Spencer Platt/Getty Images)
A Boston police officer stands near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. Three people are confirmed dead and at least 141 injured after the explosions went off near the finish line of the marathon yesterday. The bombings at the 116-year-old Boston race, resulted in heightened security across the nation with cancellations of many professional sporting events as authorities search for a motive to the violence. (Photo by Spencer Platt/Getty Images)
A Boston police officer stands near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. Three people are confirmed dead and at least 141 injured after the explosions went off near the finish line of the marathon yesterday. The bombings at the 116-year-old Boston race, resulted in heightened security across the nation with cancellations of many professional sporting events as authorities search for a motive to the violence. (Photo by Spencer Platt/Getty Images)
Boston Police stand near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. Three people are confirmed dead and at least 141 injured after the explosions went off near the finish line of the marathon yesterday. The bombings at the 116-year-old Boston race, resulted in heightened security across the nation with cancellations of many professional sporting events as authorities search for a motive to the violence. (Photo by Spencer Platt/Getty Images)
Unclaimed finish line bags are viewed near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. Three people are confirmed dead and at least 141 injured after the explosions went off near the finish line of the marathon yesterday. The bombings at the 116-year-old Boston race, resulted in heightened security across the nation with cancellations of many professional sporting events as authorities search for a motive to the violence. (Photo by Spencer Platt/Getty Images)
Debris and litter cover an empty street near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. Three people are confirmed dead and at least 141 injured after the explosions went off near the finish line of the marathon yesterday. The bombings at the 116-year-old Boston race, resulted in heightened security across the nation with cancellations of many professional sporting events as authorities search for a motive to the violence. (Photo by Spencer Platt/Getty Images)
A Boston police officer stands near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. Three people are confirmed dead and at least 141 injured after the explosions went off near the finish line of the marathon yesterday. The bombings at the 116-year-old Boston race, resulted in heightened security across the nation with cancellations of many professional sporting events as authorities search for a motive to the violence. (Photo by Spencer Platt/Getty Images)
Unclaimed finish line bags are left near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. Three people are confirmed dead and at least 141 injured after the explosions went off near the finish line of the marathon yesterday. The bombings at the 116-year-old Boston race, resulted in heightened security across the nation with cancellations of many professional sporting events as authorities search for a motive to the violence. (Photo by Spencer Platt/Getty Images)
A man walks by portable toilets near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. Three people are confirmed dead and at least 141 injured after the explosions went off near the finish line of the marathon yesterday. The bombings at the 116-year-old Boston race, resulted in heightened security across the nation with cancellations of many professional sporting events as authorities search for a motive to the violence. (Photo by Spencer Platt/Getty Images)
A National Guard soldier stands near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. Three people are confirmed dead and at least 141 injured after the explosions went off near the finish line of the marathon yesterday. The bombings at the 116-year-old Boston race, resulted in heightened security across the nation with cancellations of many professional sporting events as authorities search for a motive to the violence. (Photo by Spencer Platt/Getty Images)
A Los Angeles Sheriffs Counter Terrorism Unit officer carries an AR-15 assault rifle, as he patrols the entrance to Union Station in Los Angeles Monday, April 15, 2013. The city increased security following bomb explosions in Boston that killed two people and injured more than 80 near the crowded finish line of the Boston Marathon. (AP Photo/Damian Dovarganes)
Amtrak Explosive Detection K-9 officer Kenneth Wolf and his dog Teddy patrol the station tunnels at Union Station in Los Angeles, Monday, April 15, 2013. The city increased security following bomb explosions in Boston that killed two people and injured more than 80 near the crowded finish line of the Boston Marathon. (AP Photo/Damian Dovarganes)
A Los Angeles Sheriffs Counter Terrorism Unit deputy patrols Union Station before the start of Los Angeles Dodgers game in Los Angeles Monday, April 15, 2013. The city increased security following bomb explosions in Boston that killed two people and injured more than 80 near the crowded finish line of the Boston Marathon. (AP Photo/Damian Dovarganes)
The Minnesota Twins stand during the National Anthem following a moment of silence to honor the victims of the Boston Marathon bombing before the game against the Los Angeles Angels of Anaheim on April 15, 2013 at Target Field in Minneapolis, Minnesota. All uniformed team members are wearing jersey number 42 in honor of Jackie Robinson Day. (Photo by Hannah Foslien/Getty Images)
A U.S. flag flies at half staff on the U.S. Capitol April 15, 2013 on Capitol Hill in Washington, DC. Speaker of the House Rep. John Boehner (R-OH) has ordered to lower the flags after two people were confirmed dead and at least 100 injured after at least two explosions went off near the finish line of the Boston Marathon. (Photo by Alex Wong/Getty Images)
A U.S. flag flies at half staff on the U.S. Capitol April 15, 2013 on Capitol Hill in Washington, DC. Speaker of the House Rep. John Boehner (R-OH) has ordered to lower the flags after two people were confirmed dead and at least 100 injured after at least two explosions went off near the finish line of the Boston Marathon. (Photo by Alex Wong/Getty Images)
