A 14-year-old suspect in a Sunday night shooting that killed three teens and wounded another at a Texas convenience store was arrested on an outstanding warrant, authorities said.

“As of 30 minutes ago, we have made an arrest. Someone that we suspect to be the shooter. He is a 14-year-old teenager,” Garland Police Chief Jeff Bryan announced Monday afternoon during a news conference.

Bryan later clarified that the suspect had not yet been charged in the slayings, but he was arrested on an outstanding warrant.

His identity and the identities of the victims were not released. Bryan said the victims killed were between the ages of 14 and 16. A 15-year-old who worked at the store was wounded, Bryan said.

All of the victims were Latino boys, Bryan said. Police know two of the teens had walked into the convenience store together. But the 14-year-old victim “was just there ordering food for his family,” Bryan said.

The shooting suspect used a 40-caliber pistol with an extended magazine. The suspect fired at least 20 rounds, Bryan said.

“We want to know why. We don’t have an answer to why. We are trying to comprehend this,” Bryan said. “When it’s kids, when it’s 14- and 16-year-old kids committing acts, and victims of acts, it’s even harder for us to comprehend that.”

During the news conference, Bryan said police were searching for a male “person of interest.”

Officers responded to the scene in Garland, northeast of Dallas, just after 7:30 p.m., according to the police department in the suburban city.

They found four males inside the store who had been shot. Three were pronounced dead at the scene, while the fourth victim was taken to a hospital, Garland police said in a statement.

Surveillance video retrieved from the store showed all four of those shot inside the shop. The video then showed a “light-skinned male exit a white Dodge 4-door pickup truck, open the front doors of the convenience store, and begin firing a gun, striking the victims,” according to the statement.

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He could be seen getting back into the white truck on the passenger side before the truck took off, fleeing the scene “at a high rate of speed,” police said.

The suspect was last seen wearing a baseball hat, a blue surgical face mask and dark-colored athletic shorts. He was not wearing a shirt, according to police.

“The investigation remains active and detectives are still trying to determine what led to the shooting,” police said, urging anyone with information to call the Garland Police Department at 972-485-4840. Tipsters can also file reports anonymously by calling Garland Crime Stoppers at 972-272-8477 (TIPS).

A reward of up to $5,000 is being offered for any information that leads to the identity and arrest of the suspect.