Security beefed up in US after Boston blast
A police officer keeps alert in front of the White House during an increase in security following fatal explosions in Boston, April 15, 2013.[Photo/Xinhua]
Police officers stand guard in front of the White House during an increase in security following fatal explosions in Boston, April 15, 2013.[Photo/Xinhua]
SWAT officers stand guard after two explosions interrupted the running of the Boston Marathon in Boston, Massachusetts April 15, 2013. Two bombs ripped through the crowd at the finish line of the Boston Marathon on Monday, killing two people and injuring dozens in what a White House official said would be handled as an "act of terror." [Photo/Agencies]