A 39-year-old New Jersey man was charged with leaving an explosive device inside the Port Authority Bus Terminal, police said on Thursday.

Officers with the Port Authority Police Department first found the device inside a briefcase at Deli Plus, which is in the south wing of the main concourse, just before 5:20 p.m. on Wednesday.

When police opened the briefcase, they found a knife, bolt cutters, screwdrivers and a stun grenade refill cartridge, which was composed of a cardboard tube with a fuse assembly and black powder. The device, described as a possible “flash bang grenade,” was not assembled at the time, a police source said.

Arsenio Mason, from Jersey City, was allegedly seen on video leaving the briefcase on a chair inside the deli, according to the criminal complaint. But Mason then apparently returned to get the bag.

“I’m looking for my briefcase, I left over there,” Mason allegedly said, pointing to the chair, according to the complaint.

Mason was charged him with reckless endangerment, criminal possession of a weapon, possession of burglary tools and criminal possession of a controlled substance.

A pipe, which contained methamphetamine residue, was also found in the right pocket of Mason’s jacket, according to the complaint.

“Sorry it’s a meth pipe,” Mason allegedly said.

Mason was held in lieu of $500,000 bail for these charges, according to the Manhattan District Attorney’s Office. His next court appearance is scheduled for March 21.

Mason was also arraigned on a separate California warrant and remanded for that case.

An attorney for Mason did not immediately respond to a request for comment.

The device was taken to the NYPD’s Rodman’s Neck facilities in the Bronx for further analysis. Heat was applied to the device and it was detonated, according to the complaint.