Boston Marathon

The FBI released photos and video Thursday of two suspects in the Boston Marathon bombing and asked for the public's help in identifying them, zeroing in on the two men on surveillance-camera footage less than three days after the deadly attack.

FBI agent Richard DesLauriers said the photos of the two men came from surveillance cameras near the explosion sites. One man is seen wearing a light-colored baseball cap, the other a dark cap. The man in the dark cap set down a backpack at the site of one of the blasts, DesLauriers said.

Within moments of the announcement, the FBI website crashed, perhaps because of a crush of visitors.

Susan Walsh / Associated Press

President Barack Obama declared "there is a piece of Boston in me" as he paid tribute to a city shaken by what he has called an act of terror. He said: "Every one of us stands with you."

Obama addressed an interfaith service in the aftermath of Monday's twin blasts that killed three and injured more 170 people at the finish line of the Boston Marathon.

Julio Cortez / Associated Press

In what could be major break in the Boston Marathon case, investigators are on the hunt for a man seen in a department store surveillance video dropping off a bag at the site of the bombings, a local politician said Wednesday.

Separately, a law enforcement official confirmed that authorities have found an image of a potential suspect but don't know his name.

Associated Press

There were conflicting reports early Wednesday afternoon about whether a suspect was or was not in custody. As of 11:15 a.m. PST, sources with knowledge of the investigation were telling NPR's Tom Gjelten that an arrest had not yet been made.

Update at 5:35 p.m. ET. 'You Couldn't Ask For A Better Daughter':

Patty Campbell read a tearful statement in front of her home in Medford, Mass., Tuesday afternoon. She said her daughter, Krystle Campbell, 29, was killed during Monday's Boston Marathon bombing.

Boston University says a graduate student at the school was one of the three people killed in the bombings at the Boston Marathon.

The Chinese Consulate in New York added the third victim is a Chinese national.

In a statement late Tuesday afternoon, the school said it was not releasing the name or any other information about the student, pending permission from the family.

The explosives used in the deadly Boston Marathon bombing were contained in 6-liter pressure cookers and hidden in black duffel bags on the ground, a person briefed on the investigation told The Associated Press on Tuesday.

One of the explosives contained shards of metal and ball bearings, and another contained nails, the person said.

A second person briefed on the investigation confirmed that at least one of the explosives was made out of a pressure cooker. Both spoke on condition of anonymity to discuss an ongoing investigation.

Two bombs blew up seconds apart Monday at the finish line of one of the world's most storied races, tearing off victims' limbs and leaving the streets spattered with blood and strewn with broken glass. Three people were killed, including 8-year-old Martin Richard, and more than 170 were wounded.

A 29-year-old restaurant manager has been identified as another victim killed in the blast. 

Her father said Krystle Campbell, of Medford, Mass., had gone with her best friend to take a picture of the friend's boyfriend crossing the finish line on Monday afternoon.

William Campbell said his daughter, who worked at a restaurant in nearby Arlington, was "very caring, very loving person, and was daddy's little girl." He said the loss has devastated the family.

The third victim was a graduate student at Boston University, the school said. 

President Barack Obama says the explosions at the Boston Marathon are being investigated as an act of terror, although authorities still don't know who is responsible.

He called the bombing "a heinous and cowardly act" used to target innocent civilians.

Michael Dwyer / Associated Press

The boy who was killed in the Boston Marathon bombings was remembered by neighbors Tuesday as a vivacious 8-year-old who loved to run and climb.

Martin Richard was among the three people killed in the explosions Monday, according to U.S. Rep. Stephen Lynch, a friend of the family for 25 years. The boy's mother, Denise, and 6-year-old sister, Jane, were badly injured. His brother and father were also watching the race but were not hurt.