AUSTIN (KXAN) — An 18-year-old is in custody, charged with firing a shot at the University of Texas at Austin’s Sigma Chi house and injuring a security guard early Sunday morning.

According to an arrest affidavit, Daniel Magee was partying at the Sigma Chi fraternity house when a witness said he had to be removed by the security guard because he was “causing problems.” Police say Magee later admitted to being on Xanax and being “heavily intoxicated” the night of the party. The on-site security guard, a 44-year-old who works for Specialized Worldwide Protection, asked Magee to leave but he became upset and had to be physically removed by the guard, continued in the affidavit.

Police say when Magee got to the front gate of the fraternity house, he said he was going to come back to the party “with an AK-47 rifle to shoot up the place.” Approximately 45 minutes later, around 3 a.m., authorities say Magee came back with two of his roommates. Witnesses told police they saw one of the men pull out a gun and fired one shot in the direction of the security guard, hitting him in the foot. Security footage showed three men in the area at the time of the shooting.

Prior to the shooting, Magee asked about joining the fraternity and gave the group his number and name, which helped police track him down. A search of UT’s directory does not show Magee as a registered student. Police say his two roommates aren’t students at UT either.

Magee was arrested early Monday morning and charged with aggravated assault with a deadly weapon. When police questioned Magee’s roommates, they said they were unaware he had a weapon on him and they didn’t know what he was planning when they went to the fraternity house.

A search of Magee’s apartment in West Campus yielded an AK 47 as well as a .40 caliber weapon, but not the weapon that was used in the shooting. Magee told police he got rid of the weapon after the shooting but couldn’t tell police exactly where he discarded it. Police ask that if you find a weapon, please contact 911. Magee did not have a concealed handgun license.

In a statement, Sigma Chi said, “We are saddened by the incident that occurred after the tailgate event we hosted at our chapter house following last Saturday’s football game.” The fraternity said they will continue to work with law enforcement and will take action to ensure the health and safety of their members and guests.