BOISE, Idaho — A Porsche plowed into a crowd of spectators at a Boise, Idaho, car show, injuring 11 in a horrifying scene that saw bystanders scrambling to tend to the injured, authorities and witnesses said.

Police say the driver of the gray Porsche accelerated while leaving the Cars and Coffee event, lost control and ran into the nearby crowd lining a sidewalk. Police say the driver is cooperating in their investigation.

Boise police spokeswoman Haley Williams said there were many with serious injuries, but no fatalities had been reported by late Saturday afternoon. Some of those injured were children, Williams said.

Tom Weekes of Boise attended the event with his 12-year-old son and had just moved a few feet back on the sidewalk when the car lost control.

“My son and I were the last two people he missed,” he said. “There was a group of kids to the right of us and he hit every one of them.”

Weekes said one of young people in their teens or early 20s flew over the top of the car and landed in front of him and his son.

Six of the injured were taken to area hospitals by ambulance.

Five others were taken to hospitals in private vehicles, she said.

Justin King, a car enthusiast from Nashville, Tennessee, said the show drew about 400 or 500 cars, but only about half remained when the crash occurred shortly before the show ended.