A manhunt was underway Sunday for the man who walked into a packed party near a Texas A&M campus and opened fire, killing two people, injuring 12 more and igniting "complete chaos" as hundreds of panicked partygoers scrambled for cover.

Hunt County Sheriff Randy Meeks said the gunfire broke out just after midnight at The Party Venue in Greenville, a town of 27,000 people 50 miles northeast of Dallas.

Meeks said at least 750 people were at a Halloween party that was also celebrating homecoming weekend at Texas A&M University-Commerce, although it was not a university-sanctioned event. About 90% of the partygoers were in their late teens or early 20s, he said.

No suspect had been identified, no description was immediately released, and authorities had no motive, Meeks said. Deputies had been called to the scene to deal with parking complaints about 15 minutes before the shots rang out. Some of the first people they encountered appeared to be drunk, Meeks said.

"When the shots were fired it was completed chaos as people fled for safety and deputies attempted to locate the shooter," Meeks said.

Markeice Ford said he had just come out of the men's room when he heard six or seven gunshots. He said he ducked to the floor, looked around and saw "about three dead bodies." He said he never saw the shooter.

"I must have been close to some of it because I got blood all over my clothes," he told WFAA-TV. "I was trying to see if something happened to me because I had blood everywhere."

Deputies heard gunshots coming from the back of the building, about 15 miles from the school's campus, but could not immediately determine whether the shots were fired from inside or outside, Meeks said. Officers found the bodies of two men inside the building.

"The shooter came in the back door," Meeks said. "His first victim, we think, may have been his target victim. The rest of them were just random."

Meeks said that he does not believe the shooter poses an immediate danger to the general public but added that "we need to get him off the street as soon as possible."

Meeks said he did not know whether the two people who died were university students. Texas A&M University-Commerce President Mark Rudin said four students were treated and released at local hospitals.

Rudin said counseling services were being offered to all of the school's students.

"Last night’s tragedy ... has touched and saddened our university community," Rudin said in a statement. "Our heartfelt sympathies extend to all victims, their families, and friends."

The 12 injured included six people who were trampled or hurt by glass in the melee, according to Sgt. Jeff Haines, a spokesman for the sheriff’s department. Six others were injured by gunfire. Four of them were in critical condition and one was in good condition Sunday afternoon, he said. He did not know the condition of the sixth person. Authorities initially had said 14 people were injured, but they later revised that figure.

"Some of the injuries were from broken glass, they were breaking the glass in the windows trying to get out of the building," Meeks said. "It was mass confusion when the shooting started."

Markenya Shepherd told WFAA-TV she feared for her life when she heard gunshots. Everyone around her dropped to the floor, so she did, too, before trying to flee.

"I was trying to get out of there, glass breaking, people crying," she said. "This was out of nowhere. Everyone was chilling, then pow pow pow pow, four or five shots."

Mass shooting deaths:Texas is the state with most mass shooting deaths. Now what?

Medical City Plano spokeswoman Melissa Sauvage said the hospital received three of the wounded, all of whom were in critical condition.

Authorities initially said the weapon was a semiautomatic rifle, but Meeks said investigators now believe one gunman opened fire with a handgun.

Gov. Greg Abbott said the Texas Rangers and Texas Dept. of Public Safety were "working aggressively" alongside federal and local authorities in response to the shooting.

Texas A&M University-Commerce is the second-largest campus in the Texas A&M system with 6,000 undergraduate students and 4,000 graduate students. The school "offers a challenging education in an easy-going environment," according to its website.

Texas has been the scene of several mass shootings in recent months and years. Less than two months ago, a gunman's rampage in Odessa, Texas, left seven people dead and 25 wounded. Less than a month before that, 22 people were killed and dozens more wounded when a gunman opened fire at a Walmart in El Paso.

Contributing: The Associated Press