Shots fired at a house party in Pittsburgh early Sunday killed two 17-year-olds and wounded at least eight other people, police said.

Hundreds of people — the “vast majority” of them minors — had gathered at a short-term rental property when some kind of altercation occurred and shots were fired at around 12:30 a.m., Pittsburgh Police Chief Scott Schubert said at a midday news conference.

Schubert said there was gunfire both inside and outside the rental home, “and potentially back and forth.” Bullet casings found at the scene indicating handguns and one rifle were used, he said, and police believe there were multiple shooters.

Two male gunshot victims died at the hospital. The Allegheny County Medical Examiner’s Office identified them as Jaiden Brown and Mathew Steffy-Ross, both 17.

Eight people were also being treated for gunshot wounds, and others were injured trying to escape, Schubert said, including two who broke bones after jumping from windows. One victim was injured after a car was “shot up,” Schubert said.

George Stevens said he was outside a bar next door to the rental property smoking a cigarette when he heard what he thought were fireworks, then saw kids fleeing.

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Stevens told The Associated Press he let three girls hide in his vehicle and call their parents as bullets flew by. He said he saw someone inside the rental property holding a gun, as young people ran screaming and crying away from the building.

“It happened so quick,” he said. “It was just crazy. Kids were running everywhere.”

ShotSpotter indicated more than 90 rounds were fired, and Schubert said “we know there was a lot more than that between inside the structure and outside.” Police were processing evidence at as many as eight separate crime scenes spanning a few blocks around the rental home. Arriving officers found a “very chaotic” scene with injured victims, medics trying to treat them and people fleeing on foot and in vehicles, he said.

No arrests were immediately reported but Schubert said “it is our top priority to find out who did this and get them off the street.” He said he couldn’t comment on a possible motive, but he decried the number of illegal guns and too many people with access to them as well as the potent mixture of alcohol, drugs and guns.

“It’s heartbreaking; here we are at Easter and we have multiple families, two that won’t see a loved one,” Schubert said. “Others that are going to be — how can you even have a holiday when your child was involved in something traumatic like this?”

Allegheny General Health reported that seven people were treated at Allegheny General Hospital and one at Jefferson Hospital for gunshot wounds or other injuries, but officials declined to release their conditions or other information.

Pittsburgh Public Schools will impose a limited lockdown Monday “out of an abundance of caution,” Interim Superintendent Wayne Walters said in a statement, meaning only people with scheduled appointments will be allowed into the district’s buildings.

Neighbor Mitchell Wilston, 30, told the AP that he and his wife weren’t at home during the shooting but before leaving saw the neighborhood packed with people, with cars parked the wrong way down the street and a line outside the rented home.

“It was so obvious that there was going to be a problem — there was a line of 14-year-old kids trying to get into this place,” he said. The house has been rented for bachelorette parties or other events before, or for families of baseball players due to its proximity to the stadium, but no problems had occurred, he said.

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In the morning, Wilston said he found his wife’s white car smeared with blood, possibly from someone trying to hide behind the vehicle.

Airbnb spokesperson Ben Breit confirmed the house was rented through the company. He said the booker, who would have had to be 18 or older per Airbnb rules, has received a lifetime ban. Breit’s statement says the party was thrown without the knowledge of the host, whose listing banned parties and advertised an overnight noise curfew. Breit said Airbnb was cooperating with authorities.

Pittsburgh Mayor Ed Gainey condemned the violence, which he attributed in part to a failure to get guns off the streets and provide adequate resources to communities. He said the city would call a meeting with local leaders to get feedback on a new, citywide approach to public safety.

“The time is now for us to move with a sense of urgency to bring justice to the victims and peace to our city,” Gainey, who is in isolation because of a recent COVID-19 exposure, said in a statement.