The FBI says someone knows the identity of two suspects in the Boston Marathon bombings whose photos were released this afternoon.
The photos and video of the two suspects were unveiled at a briefing in Boston by FBI agent Richard DesLauriers, who asked for the public's help in identifying them.
The images were taken from surveillance cameras near the explosion sites. Both men were carrying backpacks. One is seen wearing a dark baseball cap, the other a white cap worn backwards. DesLauriers says the man in the white cap is seen setting down a backpack at the site of one of the blasts.
He says the suspects are considered armed and extremely dangerous, and people who see them should not approach them.
The images are posted on the FBI's website. Persons with information are encouraged to call 800-CALL-FBI. Online tips can be forwarded to bostonmarathontips.fbi.gov