PARAMUS, New Jersey - A gunman opened fire in a crowded New Jersey mall late on Monday before killing himself, officials said, sparking a mass evacuation of the complex by police who did not realise he was dead for several hours.
Richard Shoop, 20, shot at least six rounds from a modified rifle seemingly at random and without hitting anyone, before turning the gun on himself in a back area of the mall, Bergen County Prosecutor John Molinelli told a news conference early on Tuesday.
Authorities said Shoop had a history of drug abuse and drug dealing, "which may very well have been the reason why he ultimately chose to do what he did last night," Molinelli said on ABC-TV's "Good Morning America" programme.
Officials found Shoop's body in the Westfield Garden State Plaza in Paramus at about 3:20 a.m. EST (0820 GMT).
Molinelli said it appeared Shoop went into the mall with the intention of committing suicide, not to hurt others.
"He left a note," Molinelli said. "It's a bit ambiguous. I'm hesitant to say it's a suicide note. It does express that an end is coming. It could have been prison. It could have been what he did last night." Shoop used a rifle that had been modified to look like an AK-47 and that he had stolen from his brother, who owned it legally, Molinelli said.
Police had evacuated thousands of people from the mall and launched a manhunt after shoppers reported hearing gunshots sometime after 9 p.m EST, said Jeanne Baratta, chief of staff for Bergen County.
Najee Waters, 19, of East Rutherford, New Jersey, was at his sales job at an H&M clothing store when he heard what sounded like two shots ring out.
"It was frantic. Absolutely chaos," said Waters, who followed a practiced store emergency plan and rushed to a break room at the back of the store, where about a dozen workers gathered before dashing out to the parking lot. About 25 customers were in the store at the time.
The Garden State Plaza mall, owned by Australia's Westfield Group, is one of five large malls in Paramus, located about 20 miles northwest of New York City and known as a key destination for shoppers.
Two months ago, a group of al Qaeda-linked militants launched an attack on a mall in Nairobi, Kenya, that killed 67 people.