SAN ANTONIO -- An off-duty security guard opened fire on three men who were attempting to rob him, killing one of the men and wounding another, police said.

Police identified the dead man as Rudy Perez, 21.

The incident happened about 3 a.m. on Sunday in the 200 block of Navidad, shortly after Jino Velasquez, 23, arrived outside his home after working a shift as a security guard.

Velasquez said three men pulled up in black Acura, and one of the men, Perez, walked toward him with a gun.

"He (Perez) had a black bandana on around his face. As he got closer to me, I saw a weapon in his hand coming towards me. That's when I drew my weapon and I shot at him," said Velasquez.

Police said Velasquez continued to shoot as Perez jumped in the car and it sped away.

Police said the three men drove to Christus Santa Rosa Hospital, where Perez was pronounced dead. Another suspect suffered a gunshot wound to the thigh.

Velasquez said he feared for his life.

"They wanted to try me and they chose the wrong guy at the wrong night at the wrong time," said Velasquez. "I've never killed anybody. I am very sorry that he died. I didn't intend to kill him, but I feared for my life. I really feared for my life."

"They admitted they were going to rob the victim, " said Officer Joe Rios, a spokesman for the San Antonio Police Department. "This victim actually foiled his own robbery and possibly saved his life."

Rios said Perez was a documented gang member with a criminal history.

Rios said Perez was currently on probation after being convicted last year in connection with a home invasion.

Perez' girlfriend, Elena Granada, called Perez a decent person who wanted a family of his own.

"Everybody is going to miss him. He worked hard for what he wanted," said Granada. "He also put his mom and sister first. He couldn't stand seeing his friends hurt."

Granada said she did not know the two men Perez was with when he was killed.