BOSTON - A lid to a pressure cooker believed to be used in the Boston Marathon bombings was found on a rooftop at the scene.

The FBI confirmed one of the two bombs used in the attacks was made with a pressure cooker. The bombs were packed with explosives, nails, BBs and other lethal shrapnel.

The second device was housed in a metal container, however officials say there is insufficient evidence to determine if it was also a pressure cooker. The FBI and other law enforcement agencies are asking the public to come forward with any information.

The number of people injured from the bombings now stands at more than 180, and three people have died. Officials still don't know who did it or why.