A 14-year-old boy was taken into Garland police custody Monday afternoon on suspicion of fatally shooting three people and injuring a fourth at a gas station Sunday evening.

The teen is the slender, shirtless person seen in surveillance camera footage opening the store’s front door and firing at least 20 rounds, Garland Police Chief Jeff Bryan said during a news conference Monday.

The shooting killed three boys ages 14, 16 and 17, police said. A 15-year-old cook inside the store also was hurt. He remained hospitalized in stable condition Monday, police said.

Bryan did not identify the 14-year-old suspect because of his age. Officers are still searching for a male who they say drove the pickup that he and the gunman fled in.

Police are also looking for the truck, which they describe as a white, four-door Dodge Ram 1500 with a long, dark marking along the passenger side.

The 14-year-old was taken into custody shortly before 4 p.m. Monday. Bryan declined to release details about where he was found and how he was apprehended, except to say he did not turn himself in. Bryan said he didn’t know if the suspect was speaking with police or if he had an attorney. The investigation is still active, he said.

“We’re trying to complete an accurate and thorough investigation and arrest,” he said. “We owe that to the families.”

Bryan did not release the names of the victims, also citing their ages. He said the families have been notified.

A bouquet of colorful daisies sat on the curb outside the closed store Monday with a note that read: “We will forever miss you Xavier!!!”

Officers responded to the shooting call about 7:30 p.m. Sunday at the food mart of a Texaco in the 700 block of West Walnut Street, near downtown Garland. The store is next to a smoke shop and hair salon and across the street from the Garland Center campus of Dallas College.

Motive and details of what led to the shooting were still being investigated, Bryan said. Nothing was taken from the store, police said, and the investigation has ruled out robbery as a motive.

Surveillance camera footage showed the driver and shooter in the parking lot within 30 minutes of the shooting, Bryan said. The driver was seen inside the store before the shooting and the shooter was seen inside the truck.

Moments before the shooting, the driver stopped the truck in front of the store entrance. The shooter got out, crouched as he walked along the store windows carrying a .40-caliber pistol with an extended magazine, opened the store door and began shooting. Police said the shooter wore a baseball cap, blue surgical mask and dark-colored athletic shorts.

The shooter then ran to the pickup and the two fled.

Two of the victims had come into the store together, Bryan said. Another was already inside the store and was buying food for his family, said Lt. Pedro Barineau, a department spokesman.

“The second thing is we’re trying to do is support the families. The day after Christmas, they’ve lost their loved ones,” Bryan said.

Bryan said police are still trying to determine whether the shooter knew any of the victims. It was unclear whether any of them were the shooter’s intended target, Bryan said.

Anyone with information may contact Garland police at 972-485-4840.

Anonymous tips may be submitted to Crime Stoppers at 972-272-8477. A reward of up to $5,000 is being offered for information that leads to the identity and arrest of the gunman.