Explosion | featured news

A rail car filled with extremely hazardous ammonium nitrate did not cause the fiery explosion at a Texas fertilizer plant, investigators said on Tuesday, in their first statement ruling out possible sources of the deadly blast six days ago.

Federal investigators want to speak with multiple persons seen in at least one video from the Boston Marathon, according to Department of Homeland Security Secretary Janet Napolitano, backing up what FBI sources had told Fox News earlier.

Even as as President Obama pledged federal assistance to the devastated community, morning rainfall was hampering search and rescue efforts Thursday at the site of the West, Texas, fertilizer plant explosion, which killed as many as 15 people and injured 160.

Investigators poring over photos and video from the Boston Marathon have an image of a potential suspect in the deadly bombing but do not know his name and have not questioned him, a law enforcement official said Wednesday.

Authorities investigating the deadly bombings at the Boston Marathon have recovered a piece of circuit board that they believe was part of one of the explosive devices, and also found the lid of a pressure cooker that apparently was catapulted onto the roof of a nearby building.

The two bombs that ripped through the crowds at the Boston Marathon, killing three people and wounding more than 170, were fashioned out of pressure cookers and packed with shards of metal, nails and ball bearings, a person briefed on the investigation said Tuesday.

David Gergen says people there will grieve for many days, but anyone who thinks an attack on this city will produce fear, doesn't know the bravery and spirit of this historic town.

New developments: The identity of a second victim was revealed Tuesday. Krystle Campbell, a 2001 graduate of Medford High School, died in the attack, Medford Mayor Michael McGlynn said.

US President Barack Obama has condemned the bombings at the Boston Marathon as a "terrorist act". He said the attack had been a "heinous and cowardly act", but said it was not yet known who carried out the attack and why. The FBI has said there are "no known additional threats" beyond the two bombs which went off. Three people were killed, including an eight-year-old boy, and more than 150 injured by the bombs.

Kevin Harris died in 'a pretty powerful explosion' at his home, which was wrapped in foil. Family members describe him as brilliant and gentle. An essay in his name expresses fear of the government.