A Utah man accused of killing a teenage brother and sister in what's being called a senseless slaying over a T-shirt has been arrested on allegations that could become a capital murder case, authorities said Friday.

Mario Cervantes-Angel, 28, fired several shots after Jose Izazaga, 16, came out with a knife to defend his sister because she was being pushed around, police said. The fight started after another man accused Abril Izazaga, 15, of taking a shirt late Wednesday, according to Lt. Lex Bell of Salt Lake County's Unified Police Department.

The girl died at the apartment complex in the Salt Lake City suburb of Midvale, and her brother died at a hospital shortly after.

The group scattered, but several witnesses identified Cervantes-Angel as the person who fired the shots, according to a jail booking statement. He was arrested the day after the shootings.

The man who originally started the argument turned himself into to police, but hasn't yet been formally arrested and his name hasn't been released.

No attorney was immediately listed Cervantes-Angel in court records, and a search of public records showed no listed phone number.

Jail records say he's from Mexico and his also being held on an immigration violation. He's been arrested on suspicion of two counts of aggravated murder, a charge that carries the possibility of the death penalty. Prosecutors haven't yet filed formal charges in the case.

Members of the Izazaga family say the two slain siblings shared a tight bond. They were the youngest of nine siblings and both had birthdays in July.

Their older brother Kenny Lopez has said the man who started the confrontation was a longtime friend of Jose Izazaga and spent a lot of time at the house and sometimes stayed there when he didn't have a place to stay.