One person was killed and at least eight were injured in a mass shooting Sunday at a community center in Pennsylvania where over 150 people were attending a private party, police officials said.

Law enforcement responded to the Chevy Chase Community Center in White Township, about 50 miles northeast of Pittsburgh, around 12:35 a.m. Nine people, between the ages of 18 to 23, were shot, including a 22-year-old Pittsburgh man who died at the scene, police said.

No arrests have been made in connection with the shooting and little information has been released about potential suspects. During a news conference Sunday afternoon, Pennsylvania State Police Lt. Col. George Bivens said investigators believe more than one shooter was involved; however, he did not say how many.

Bivens added that investigators believe the events were “isolated to the attendees at that party” and did not think there was a threat to any nearby communities, despite no arrests being made.

Among the wounded was an 18-year-old man from Chicago, who was critically injured, and an 18-year-old man from Florida, according to a news release from the Pennsylvania State Police. The others who were shot are from Pennsylvania, including three men – ages 19, 20 and 22 – two 19-year-old women and a 23-year-old woman.

Two of the young adults injured were students at Indiana University of Pennsylvania, which is less than three miles from the community center.

Mounted unit arrived as suspected gunmen opened fire

Following a noise complaint, a mounted police unit was called to the community center about a half hour before the shooting occurred, Bivens said.

When they got there, police heard gunshots inside the building. More than 150 people were believed to be at the event when gunfire erupted.

“You can imagine the chaos that would ensue from a number of gunshots in a relatively confined space,” Bivens said at the news conference. “People dove through windows, people ran through doors, ran through porch railings, trying to get away from that scene.”

Neighbors said there were 'people everywhere crying and screaming'

Neighbor Robert Miller said he and his wife heard loud music coming from the community center as they were getting ready to go to bed.

“Then all of a sudden, I heard about 20 gunshots,” Miller told the Tribune-Review. “There was people lying on the edge of the sidewalk out there. It’s terrifying.”

His wife, Ellen Ober, said, “There were people everywhere crying and screaming.”

The wounded were taken to hospitals throughout Pennsylvania. On Sunday evening, six remained hospitalized, one critically, while two had been treated and released.

At the scene of the shooting, police recovered "multiple firearms," many shell casings as well as clothing and cell phones.

The combined monetary reward for information leading to arrests and prosecutions in the case is up to $15,000.

There have been at least 540 mass shootings in the United States with at least four victims since Jan. 1, according to the Gun Violence Archive, a nonprofit publicly sourced database that defines a mass shooting as at least four people struck by gunfire, not including the shooter.

The Associated Press contributed to this report.