West Mifflin, Pa. (AP) — Three people including two teenagers were shot late Saturday at an amusement park southeast of Pittsburgh, which was kicking off a Halloween-themed festival.

Police said two 15-year-olds and an adult man were injured during the shooting reported around 11 p.m. at Kennywood Park in West Mifflin, Pennsylvania. The victims were treated at hospitals and expected to recover, KDKA-TV reported.

Authorities said an argument between two groups of teenagers prompted the shooting by a suspect described as a male wearing a mask and black hoodie, KDKA-TV reported.

Kennywood had functioning metal detectors and security personnel were on duty, police said, leaving the unanswered question of how a gun entered the park.

Police are investigating using the park’s security cameras and witness statements, KDKA-TV reported.

The Pittsburgh Public Safety Department posted a tweet around midnight saying its officers “are assisting with the reports of shots fired at Kennywood.”

Kennywood posted a statement on Twitter around 12:30 a.m. Sunday announcing the park’s temporary closure and cooperation with authorities.

“The park is closed for the night and all guests have exited. We are aware of a situation that occurred this evening and are working with local law enforcement. The safety of our guests and Team Members are our top priority. Members of the park’s security, Allegheny County, and West Mifflin police departments were already on site and immediately responded,” the post said.

An advisory posted by the West Mifflin Borough at 1:50 a.m. Sunday said Kennywood Boulevard had been reopened.

The park released a statement on Sunday, Sept. 25, stating the park will be closed on Sunday and will reopen on Friday, Sept. 30:

We are greatly saddened by the violence that occurred last night. Our thoughts are with those who were injured as a result of the incident, as well as all guests and team members affected by what happened. We have made services available for team members in need of support at this time.

We are closely collaborating with police as they investigate. Our entry security protocols include a state of the art weapons detection system put into place at the start of this season, video scanning, and bag checks. We regularly supplement our park security staff with officers from the Allegheny County Police Department and West Mifflin Police Department, who were contracted to support our teams during operating hours, including Saturday evening. We will continue to cooperate with authorities throughout their investigation.

The park is closed Sunday, September 25. We will reopen as scheduled on Friday evening, September 30, and will continue to provide updates as more information becomes available.

Mark Pauls, Kennywood General Manager

Kennywood was celebrating the first night of its Phantom Fall Fest, scheduled to run through Oct. 16, according to the park’s website. The website advised the park would reopen on Friday, Sept. 30, with tickets for the day of the shooting valid on any other day of Phantom Fall Fest. 

The website bills the park as a family fun destination featuring seven roller coasters and rides for children.