Three teenagers were killed and another one was injured in a shooting at a gas station in south central U.S. state Texas over the holiday weekend, police said Monday.

The suspect, a 14-year-old boy, was arrested on Monday afternoon, said Police Chief Jeff Bryan in the Dallas suburb of Garland.

In surveillance video of the shooting, which took place on Sunday night, the shooter got out of the passenger side of a pickup truck, walked up to the front door and opened fire into the gas station convenience store from the doorway. Police said he fired more than 20 rounds from a .40 caliber pistol.

The shooter then got back into the pickup and fled with a male driver, whom police said they are still searching for.

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The dead were three boys aged 14, 16 and 17, police said. The youngest, identified as Xavier Gonzales, was ordering tacos for his family when he was killed. Bryan said it appears Gonzales was just in the wrong place at this wrong time.

The wounded, a 15-year-old store employee who just started to work at the taqueria in the store last week, was now hospitalized in stable condition, said the police.

Investigators are still trying to determine a motive, according to local media reports.