Two people were killed and six others wounded when a shooter opened fire at an off-campus homecoming party near Texas A&M University-Commerce campus just before midnight.

The shooter is still at large, authorities say. Police said he used a 9mm handgun and that earlier reports that the weapon was a rifle were erroneously based on replica shells scattered around the party space as decorations.

A witness told police that the gunman appeared to “pick out one individual” for his first victim and then continued shooting, Hunt County Sheriff Randy Meeks said at a morning press conference.

Four of the wounded were in critical condition. Six others were injured in the frantic escape.

“It was mass chaos with people trying to exit the building,” Meeks said. “Some of the injuries were from broken glass. They were breaking the glass of the window trying to get out of the building.”

The shooting took place at an 8,000-square-meter event space called The Party Venue, which was holding a Halloween party called “Twerk or Tweet” to mark the end of the university’s homecoming week. Oxford said that while it was a homecoming party, it was not sanctioned by the university, according to the Associated Press.

Authorities say about 750 people were at the event. WFAA-TV Channel 8 reports that local sheriff deputies were on the scene before the shooting took place responding to illegal parking, and that the venue had private security guards but that none of them were able to return fire. Deputies say they heard gunfire about 15 minutes after they arrived.

Video purported to be from the scene of the shooting posted on social media shows people on the ground outside the venue with many others screaming in the background.

“I could hear, like, windows breaking and people screaming for their lives,” Cherise Sierra told NBC-DFW.

University spokesman Michael Johnson confirmed the shooting, noting that it did not occur on campus, and saying he could not confirm whether any students are involved. “Our thoughts and prayers are with the victims, families, and friends of those affected by this morning’s shooting in Greenville, Texas,” the university said in a statement.

The sheriff said his office had never handled such a large shooting. He noted that his staff was supposed to attend a seminar on mass shootings next week.

“Wish we could have had it a week before now,” Meeks said.