Updated

A 15-year-old boy asleep in his bed was fatally shot Thursday by a bullet fired from an apartment below.

Bukhari Washington was found by his mother, who ran into his room after she heard the shot about 9 a.m., police said.

Police said a single round from a military-style semiautomatic rifle pierced the floor of the teen's room and struck him in the head. He was pronounced dead at nearby University Hospital.

A short time later, detectives arrested downstairs neighbor Terrance Perry, 19, who faces an aggravated manslaughter count and weapons charges. Police said Perry led them to his girlfriend's vehicle where he hid the weapon.

According to Police Director Garry McCarthy, Perry said he was "fiddling" with the Norinco SKS rifle when it accidentally fired. Perry told police he had obtained the rifle on the street.

Police were trying to corroborate his story and claims by neighbors that he got the gun for protection after being robbed multiple times. But McCarthy called it "absurd" that someone would use such a high-powered weapon for self-defense.

"If somebody wanted a weapon for protection, this is not the gun — I'm sorry," McCarthy said. "I just can't accept that as an excuse."

He said the weapon is capable of piercing concrete.

"We're seeing Russian soldiers invading Georgia with these kinds of guns on their backs," McCarthy said.

Newark Mayor Cory Booker issued a statement calling Washington's death "tragic and unacceptable" and said it highlighted the importance of getting guns off Newark's streets.

"This violent incident is further proof of the work that still lies before us, and the importance of passing and enforcing legislation to curb access to illegal firearms on the streets of New Jersey's cities," Booker said.

By Thursday afternoon, friends had tacked a photo of Washington, whom many called "Kari," to a fence post in front of the housing complex where he lived across the street from the University of Medicine and Dentistry. The photo was framed by two paper signs that read, in large block letters: "Enough is Enough."

Several teens who knew Washington described him as a quiet, loyal friend who loved basketball and collecting sports hats. They said the Central High School student worked at a local recreation center at its summer camp program.

Jalissa Robinson, 15, said she last saw Washington early Thursday morning, after they had stayed up talking all night with a group of friends in the complex's courtyard.

She said they had made plans to go to see the horror movie "Mirrors" later in the day, but both were heading home first to take a nap.

"We broke dawn. We were all out here until about 7 a.m., and he went home to get some sleep because he was tired," Robinson said. "I woke up and my sister said: 'You heard about Kari Washington?' and I just broke down — I didn't even brush my teeth, I ran out of the house."

Robinson said they chose to write "Enough is Enough" on the memorial poster because they had heard the man who shot him was also a teenager.

"Who would be playing with a gun at this age?" Robinson said. "Who would let people in their house play with a gun at that age?"