Two sets of scavengers played roles in the investigation of the bombing rampage that terrorized people in New York and New Jersey over the weekend, authorities said Monday.

On Sunday night, two homeless men grabbed a backpack left in the trash near a train station in Elizabeth, New Jersey, only to discover that it contained several apparent pipe bombs. The men quickly reported the find to police, Democratic Elizabeth Mayor Christian Bollwage said.

A day earlier, two men walking down a New York City street made off with a rolling backpack that someone had left on the sidewalk about 15 minutes earlier.

But before they walked away, they removed a pressure cooker that had been concealed inside it, New York Police Department Chief of Detectives Robert Boyce said. The pressure cooker later was found by state police troopers after a similar device exploded nearby, injuring 29 people.

The unexploded device was then examined for clues to the bomber’s identity.

Police found out that the two men had handled the device only when they looked at surveillance video.

“They looked like they were two gentlemen just strolling up and down Seventh Avenue, at the time,” Boyce said. “Once they picked up the bag, they seemed incredulous that they had actually picked this up off the street, and they walked off with it.”

Asked if it was possible that the scavengers, in handling the bomb, might have jostled it enough to disable its trigger, Boyce said he couldn’t say for sure.

“It’s difficult to say right now if they at all, inadvertently perhaps even, pulled a wire,” Boyce said.

He said the men were being sought as potential witnesses.

Earlier Saturday, a pipe bomb blew up in Seaside Park, New Jersey, before a charity race to benefit Marines. No one was injured.

An Afghan immigrant wanted in the bombings was captured Monday after being wounded in a gunbattle with police that erupted when he was discovered sleeping in a bar doorway, authorities said. His arrest came just hours after police issued a bulletin and a photo of him.

The man, a naturalized U.S. citizen, lived with his family in an apartment in Elizabeth over a fried-chicken restaurant owned by his father.

(AP)