No one was in custody, Boston Police Commissioner Edward Davis said Tuesday. But officials said they know of no other imminent threats related to the explosions Monday.
"Two and only two explosive devices were found yesterday," said Massachusetts Gov. Deval Patrick at a news conference Tuesday morning. "All other parcels in the area of the blast have been examined, but there are no other unexploded bombs found."
The explosives 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.
Mr. Davis said the course was swept for explosives Monday, early in the morning and an hour before the first runner crossed the finish line. But he said that didn't preclude someone from planting devices after the last sweep. No unexploded devices were found after the blasts, officials said, though they did investigate some suspicious items that didn't turn out to be dangerous.
The tally of those injured in the bombings increased to 176, with 17 in critical condition and three dead, police said.