Two people were killed and 12 others injured when a gunman opened fire at an off-campus college party in Texas around midnight on Saturday.

Authorities were searching on Sunday for the gunman. They believed he may have been targeting just one person at the party of about 750 people outside Greenville, some 15 miles from Texas A&M University-Commerce.

Authorities originally said two were killed and 14 injured. A spokesman for the Hunt county sheriff’s office said the injured included six people who were trampled or hurt by glass in the melee.

Sgt Jeff Haines said six others were injured by gunfire. He said four were in critical condition and one was in good condition. He did not know the condition of the sixth person.

The president and CEO of Texas A&M University-Commerce, Mark Rudin, posted a statement on Facebook that said the university was reaching out to four injured students.

Rudin said there was “a tremendous amount of misinformation” about the shooting and counseling services were available to all students.

The shooting took place at what Hunt county sheriff Randy Meeks described as a Halloween and homecoming party, though officials said it was not a school-sanctioned event.

Meeks described “complete chaos”, with hundreds fleeing. Authorities believe there was one male shooter who entered the venue through the back door and began firing with a handgun, Meeks said.

The two people killed were both male, Meeks said, but he did not know if they were A&M-Commerce students. He said most of the people at the party were in their late teens and early 20s. Some of the partygoers were wearing costumes, he said.

Word of the shooting spread online, with many sharing graphic video purported to show seriously wounded victims lying on the ground as crying and screaming could be heard in the background.

“I just briefly saw one that was a very graphic video,” Meeks said. “I don’t know that’s going to help anything at all.”

Meeks said the party was held at a facility called The Party Venue and the owner was cooperating with authorities. The venue sits along a highway in a rural area some two and a half miles from the Greenville city limits. Meeks said he was not aware of any surveillance video.

Outside the venue, Halloween masks and other debris were strewn about. Pools of blood could be seen on the ground.

A patrol sergeant and deputy were at the venue when the shooting happened, having been called for complaints about illegal parking, Meeks said. An off-duty Farmersville police officer was also there, working as security.

Authorities were questioning someone who appeared to be intoxicated when they heard gunshots from the back of the building, Meeks said.

Meeks praised the patrol sergeant and deputy, saying the sergeant quickly determined that one of victims had life-threatening injuries and transported that person to a hospital, while the deputy triaged others until paramedics arrived.

The shooting came as Texas A&M University-Commerce, east of Dallas, celebrated homecoming weekend.

It is the second-largest university in the Texas A&M University System. The school was founded in 1889 and was known by several names, including East Texas State University, before joining the Texas A&M system in 1996. The university has around 6,000 undergraduate students and 4,000 graduate students.