The authorities were responding to a reported shooting on Saturday at a Walmart distribution center in Red Bluff, Calif., according to an employee who was there.
The employee, Franklin Lister, 51, said he had just clocked into his afternoon shift when an employee ran down the hallway shouting: “Active gunfire! Active shooter!”
Mr. Lister said he had seen blood dripping from his colleague’s arm.
“That’s when I realized it wasn’t a drill,” he said. Red Bluff is about 130 miles north of Sacramento.
It was not immediately clear if there were any fatalities. The Tehama County Sheriff’s Office did not immediately respond to a request for comment.
Mr. Lister and his team ran out the nearest fire exit.
As they were running, he said, they heard 50 to 60 gunshots — at which point they picked up their speed and helped each other over a barbed-wire fence. When he looked back at the building, he saw that a white vehicle had crashed into an entrance, he said.
“To hear that much gunfire, it was frantic,” said Mr. Lister, who unloads deliveries that are then repackaged and shipped to Walmart stores. “People were running as fast as they could move.”
An employee of a nearby shop said she had seen 15 to 20 fire trucks, law enforcement vehicles and ambulances driving toward the distribution center.