PINELLAS PARK — On the other side of the fence that separates the Walmart Neighborhood Market on U.S. 19 from a few blocks of mobile homes, the gunshots sounded like a “sonic boom.”

That’s how Theresa Caine, 53, heard it — one long collision of rounds fired into a gray morning.

Brian Dutton, 43, had just woken up with his family about 11 a.m. and was drinking coffee when he heard the blasts.

“Like a cannon going off,” he said.

A neighbor hurried around the corner to take a look at the parking lot next door. He saw a body on the ground.

Police said a Walmart employee in his early 20s was in back of the store at 6900 U.S. 19 on a break when two men in a white car pulled up, got out and opened fire. Walmart identified the employee as Terrell Williams, but did not provide his age or hometown, saying the company’s “thoughts and prayers are with the family.”

“We are assisting law enforcement however possible,” a spokesman wrote in a statement.

Police said the attack was targeted. They did not believe the shooting was motivated in any way by his employment with Walmart. Investigators said the vehicle involved was a four-door sedan. They interviewed multiple witnesses but had not announced any arrests by late Friday afternoon. Surveillance cameras on the corner of the building apparently recorded the incident.

Moments after the blast, Dutton said, he hopped the fence into the Walmart parking lot. He saw the man on the ground with eight to 10 bullet holes from knees to waist. The wounds were about the size of half dollars, Dutton said. Blood poured from the man’s body.

He wore blue jeans and a Walmart employee vest.

Dutton said he tried to keep the man alert. “You’ve got to stay with us.”

The man said his name but Dutton couldn’t quite make it out. Darrell? Terrell? “Just stay with us. Help is coming.”

A couple of other people rushed in and pressed their shirts into the man’s wounds, Dutton said.

Soon, they no longer felt his pulse. One woman tried to perform chest compressions.

Dutton noticed shell casings around them, some rifle rounds and others from a smaller handgun.

Walmart remained open early Friday afternoon as investigators cordoned off a back section of the parking lot, to the left of the entrance. The shooting scene was directly behind the store, just out of sight of arriving news trucks.

Walmart employees took breaks by the posts on the sidewalk, striped with candy cane ribbon for the holidays, chatting on their phones and peering back at the forensic investigators picking evidence off the pavement.

Times staff writer Sara DiNatale and staff photographer Douglas R. Clifford contributed to this report.