Two people have been killed and at least a dozen injured in a mass shooting at a university homecoming party in Texas.

Hundreds of students were gathered at The Party Venue in Greenville, near Dallas, to celebrate the start of a new term at Texas A&M Commerce College.

With 750 people in the building, someone with a semi-automatic rifle opened fire.

Graphic footage of the aftermath posted on social media showed several injured people on the ground inside the venue and dozens running away from the building.

“We’ve got a bunch of walking wounded,” a Hunt County deputy said on the scanner, according to a WFAA reporter.

Texas mass shooting: Two killed in attack at homecoming party Show all 10 1 /10 Texas mass shooting: Two killed in attack at homecoming party Texas mass shooting: Two killed in attack at homecoming party Two people have been killed and at least a dozen injured in a mass shooting at a university homecoming party in Texas EPA Texas mass shooting: Two killed in attack at homecoming party Hundreds of students were gathered at The Party Venue in Greenville, near Dallas, to celebrate the start of a new term at Texas A&M Commerce College EPA Texas mass shooting: Two killed in attack at homecoming party Halloween masks litter the ground at the scene where the deadly shooting took place AP Texas mass shooting: Two killed in attack at homecoming party With 750 people in the building, someone with a semi-automatic rifle opened fire The Dallas Morning News via AP Texas mass shooting: Two killed in attack at homecoming party Deputies were already at the scene due to a parking complaint when they heard gunshots coming from the back of the building, chief deputy of Hunt County Sheriff’s Department, Buddy Oxford, told reporters The Dallas Morning News via AP Texas mass shooting: Two killed in attack at homecoming party A single shoe and a costume hat rest on the ground AP Texas mass shooting: Two killed in attack at homecoming party Officials work at the crime scene The Dallas Morning News via AP Texas mass shooting: Two killed in attack at homecoming party Bodies are removed from the Party Venue EPA Texas mass shooting: Two killed in attack at homecoming party Officials work a crime scene The Dallas Morning News via AP Texas mass shooting: Two killed in attack at homecoming party Chief Deputy Buddy Oxford of the Hunt County Sheriff's Department addresses members of the media The Dallas Morning News via AP

The shooter was still at large several hours later.

Deputies were already at the scene due to a parking complaint when they heard gunshots coming from the back of the building, chief deputy of Hunt County Sheriff’s Department, Buddy Oxford, told reporters.

Three air ambulances took some victims to a trauma hospital, while others were taken to hospitals in Greenville, and neighbouring Quinlan and Commerce, officials told reporters at CBS‘ Dallas branch.

No official information has been offered about the identity or whereabouts of the shooter. The FBI were also at the scene on Sunday morning, Mr Oxford said.

Greenville, where students were attending the unofficial homecoming party, is 15 miles away from the university campus.