A campus police officer in San Antonio, Texas is under investigation after shooting and killing an unarmed student at an off-campus traffic stop.

At a press conference on Friday, Lt. Cindy Pruitt of the Alamo Heights Police Department said that an altercation occurred when University of the Incarnate Word Cpl. Chris Carter pulled over 23-year-old Robert Cameron Redus just a few blocks off campus at around 2 a.m Friday morning.

A witness who did not wish to be identified recalled to KSAT that the officer never warned Redus before shooting him.

"I didn't hear him say anything like, 'Get down on your hands and knees,' you know? I didn't hear him say anything. He just started shooting," the witness said. “He emptied the gun on him.... Boom, boom, boom. Six shots -- five or six.”

However, 22-year-old Mohammad Haidarasl -- a resident of Treehouse Apartments in Alamo Heights -- did hear Redus speak to the officer.

“I heard (a man) say, 'Oh, you're gonna shoot me?' like sarcastic almost,” Haidarasl explained to the San Antonio Express-News.

Friends of Redus, like Sarah Davis, described the Houston resident as "not an aggressive person at all."

“I just don’t understand how a campus police officer was off campus and he got shot by the campus police officer," UIW senior Katie Bosworth told KSAT.

But according to university policy, officers have the authority to "patrol all UIW property, parking lots, residence halls and facilities" near campus.

Lt. Pruitt said on Friday that the investigation would try to determine if Redus had a weapon or was threatening Carter.

“This is really in its preliminary stages,” Pruitt pointed out. “This investigation will go on for days.”