A teenager was killed and another was critically injured when gunfire erupted at a popular Halloween hayride attraction in a Pittsburgh suburb, and police said the suspected gunman remained on the run Sunday.

       The shooting unfolded around 8:15 p.m. Saturday at the Haunted Hills Hayride, about 13 miles southeast of Pittsburgh, according to the Allegheny County State Police.

       Police said gunfire broke out near the ticket booth about 15 minutes before the annual charity event was set to open for the first night in a run scheduled to go through Halloween.

       WTAE

       Police investigate the scene of a shooting at the Haunted Hills Hayride in North Versailles, Pennsylvania, Sept. 11, 2021.

       Several hundred people, including parents and children, were waiting to get into the event when multiple shots were fired, sparking a chaotic scene of people scrambling to get out of harm's way, according to police.

       Law enforcement sources told ABC affiliate WTAE in Pittsburgh that the shooting appeared to have stemmed from an argument near the ticket booth.

       Lt. Venerando Costa of the Allegheny County Police Department said at a news conference that two 15-year-old boys were shot and taken to an area hospital, where one was pronounced dead and the other was in critical condition. Their names were not released.

       WTAE

       Police investigate the scene of a shooting at the Haunted Hills Hayride in North Versailles, Pennsylvania, Sept. 11, 2021.

       Costa said witnesses described the suspected gunman as Black, 15 to 17 years old, 5 foot 9, with short hair and wearing dark blue cargo shorts and carrying a black backpack.

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       It was unclear if the suspect fled the scene on foot or in a vehicle.

       No other injuries were reported.

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       "What goes through my mind when a 15-year-old gets shot at a hayride? I think it's a terrible shame," Costa said. "Anybody could have been hurt."

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       The Haunted Hills Hayride, which also features a haunted trail lined with actors dressed in Halloween costumes, is an annual charity event to benefit the Autism Society of Pittsburgh.