Special Agent Rick DesLauriers of the FBI, who is leading the investigation of the Boston Marathon bombings, just held a press conference in which he revealed that there are two suspects. The FBI released photographs (above) and video of two men believed to be responsible for the attacks.

The FBI showed video of the two men walking through the crowd, each wearing a backpack, presumably with a bomb inside. They appear calm, and don't attract any attention from anyone they pass by:

Apparently there is also video of the man in the white cap, called "Suspect No. 2," actually planting one of the bags that later exploded, but they did not release that footage. The two suspects are said to have placed the bombs in their locations mere minutes before the explosions.

DesLauriers says he considers both men "armed and extremely dangerous," but when asked if there was any threat to the public right now, he said, "There is no additional, imminent danger that we are aware of right now."

The FBI's website crashed almost immediately after the press conference began, with so many people trying to get a look at the images.

If you recognize either man or have any other information you feel might be helpful, the FBI has set up a website for you to share what you know: bostonmarathontips.fbi.gov. You can also call 1-800-CALL-FBI.