An explosive device found in a trash can near a train station in a New Jersey town outside New York City detonated early Monday as a bomb squad was attempting to disarm it with a robot, officials said.
There was no immediate report of injuries or damage.
The mayor of the Elizabeth, whose population is 60 percent Hispanic, said the FBI was working to disarm one of five devices found in a bag spotted by two men at Sunday night.
Mayor Christian Bollwage said the men had reported seeing wires and a pipe coming out of the package. He warned that other explosions were expected.
FBI agents and police converged on an apartment above a fried chicken restaurant near the train station before 6 a.m. Monday, but it was not clear whether their search of the dwelling was connected to the explosion.
New Jersey Transit service trains resumed service on the Northeast Corridor and North Jersey Coast Line at 5:30 a.m. Monday, but they faced residual delays because service was suspended after the devices were found.
Amtrak was operating on a modified schedule.
Train passengers reported being stuck on Amtrak and NJ Transit trains for hours Sunday night, while some trains moved in reverse to let passengers off at other stations. Amtrak said 2,400 passengers were affected and trains were being brought in to other stations for people to get other transportation.
It wasn't clear when the Elizabeth station would be open, a threat to cause major issues on the Monday morning commute into New York.
The discovery of the suspicious package came a day after an explosion in Manhattan injured 29 people, and an unexploded pressure-cooker device was found four blocks away in New York City. Also Saturday, a pipe bomb exploded about an hour from the Elizabeth train station in Seaside Park, New Jersey, forcing the cancellation of a military charity 5K run. Officials said it didn't appear that those two incidents were connected, though they weren't ruling anything out.
Investigators didn't immediately comment on whether they thought the Elizabeth incident was connected to either of the two blasts.
Bollwage said that he wasn't willing to say that Elizabeth had become a target and that it was possible that someone worried about the authorities was trying to get rid of the package.
"I'm extremely concerned for the residents of the community, but more importantly extremely concerned for everyone in the state and country where someone can just go and drop a backpack into a garbage can that has multiple explosives in it," Bollwage said. "You have to wonder how many people could have been hurt."
Based on reporting by the Associated Press.