WALKER, Mich. (WOOD) — A driver was seriously hurt Monday morning when a rock fell out of a passing trailer and hit him, causing him to crash, Walker police say.

“He was pretty, pretty bad,” said Amy Jarmer, who was at work when the car crashed into the lawn outside and rushed to help the driver.

It happened around 8:50 a.m. in the 2200 block of Turner Avenue, south of West River Drive in Walker.

The Walker Police Department says the rock crashed through the windshield of a northbound vehicle, striking the driver in the head and knocking him unconscious. That caused him to crash into a power pole, snapping it in half. The car finally stopped when it hit some shrubs.

The rock, which is about 8 inches by 7 inches and weighs about 11 pounds, fell off of a dump trailer being hauled by a southbound semi-truck. The rock was found in the back seat of the car.

The driver, a 48-year-old Grand Rapids man, was rushed to the hospital. He remained in critical condition Wednesday.

Jarmer said it’s common to see trucks in the area carrying unsecured materials.

“It’s scary for all of us. It’s scary. We drive through here constantly,” she said. “It could have happened to any of us.”

Wednesday, Walker police said they had a lead on the truck involved, a white semi without a sleeper cab hauling a black dump trailer. They did not think the driver was aware of the crash.

It’s unclear if the truck driver will face any penalties.

“Hopefully this will bring some awareness to some of these companies to make sure that they have their vehicles covered,” Jarmer said.

Anyone with information is asked to call police at 616.791.6887 or Silent Observer at 616.774.2345.