By Jessica Michele Herring (staff@latinospost.com) | First Posted: Nov 05, 2013 01:14 PM EST

A gunman who fired shots in a mall in northern New Jersey Monday night was found dead early Tuesday. 

The shooter, Richard Shoop, 20, of Teaneck, N.J., fired at least a half dozen bullets into the Westfield Garden State Plaza Mall on Monday night. He was found dead just after 3 a.m. on Tuesday morning. John Molinelli, the Bergen County, N.J. prosecutor, said that it appears the gunman, who had a history of drug abuse, shot and killed himself, TIME reports. 

The gunman opened fire just before 9:30 p.m. at the mall, which is the largest shopping mall in New Jersey. Police say Shoop walked into the mall dressed in black and wearing a motorcycle helmet. Witnesses say Shoop walked through the mall, shooting security cameras and firing off about half a dozen shots in total. 

The mall was quickly put on lockdown as customers and mall employees ran for the exits. Shoop then went to an area of the mall that has limited access and shot himself to death. No one was injured in the shooting. 

Molinelli said they found his body "very, very deep in an area that was under construction" in the mall, according to The New York Times. Shoop was found with a firearm that was altered to look like an AK-47 assault rifle, Molinelli said.

"It was a lawful weapon that was owned by his brother," he said. Authorities believe that Shoop stole the gun before heading to the mall. "Thousands of people began to run out of the mall," Molinelli said. "At least 400 patrons were locked into whatever store they were in at the time."

Fabio Rocha of North Bergen, N.J., got a frenzied call from his wife, Maria, from inside the mall, saying she had just walked past a man with a "big gun," the NYT reported. Many witnesses said that he did not aim his weapon at people, and did not try to harm shoppers. Besides shooting security cameras, he also shot his gun in the air. 

Authorities suggest that Shoop was trying to commit "suicide by police," but that when he did not run into a police officer, he took his own life. Police found a note in Shoop's home, but would not comment on its contents. 

Shoop, the middle child of three siblings, lived with his parents and a pitbull in a typical, tree-lined residential neighborhood. Shoop had tattoos on his shoulder and liked to drive his blue Nissan Z300X car and motorbike at high speeds, friends said. A friend, who identified himself as David, said Shoop smoked marijuana and was arrested once. 

Molinelli told reporters that Shoop was "a 20-year-old kid who dabbled in drugs."

Mary Jane Tipton, 55, a neighbor, told reporters she could not understand what would drive him to commit suicide in such a way. "I've known him since he was a little boy," she said. "I would never in a million years think this."

"He was just one of the kids who lives in the neighborhood, a very nice young man," said Daniel Klapper, who has lived in the neighborhood since Shoop was born. 

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