PITTSBURGH — A school bus driver was charged with running over a 67-year-old woman with his bus then leaving the scene. Ernest Brevard, 71, of Wilkins Township, had just dropped off students from Pittsburgh at a Catholic school in Forest Hills when his bus allegedly ran over Alberta Slaczka, Allegheny County police said in a criminal complaint filed Friday. The accident, which critically injured Slaczka, happened about 8 a.m. Wednesday.

Police did not immediately charge Brevard because they didn’t know at first whether the driver even realized he had hit the woman with the lumbering vehicle. But that changed after “witnesses came forward who saw Brevard run over the victim, circle the area to see that he struck a person, then flee,” police said.

Brevard was interviewed at his home Thursday night and denied striking the woman. He told police he was aware of a body lying in the road, but that he just got out of his bus briefly to see what was going on along with other bystanders, according to a criminal complaint.

That’s not what Tom Wypychowski, named as a key witness by police, told WTAE-TV that he saw.

“I saw something roll up under the school bus. I didn’t think anything of it, it was 50 feet ahead. Once I pulled up and realized it was human, it smacked me in the face,” he said. “It was sheer shock that you could run someone over and not actually stop. I won’t even run over a dog without trying to find the owner, but to do it to a human being is almost unthinkable.”

Detective Scott Scherer said that Wypychowski didn’t come forward immediately because he believed the driver had already turned himself in.

Wypychowski “was actually following the bus, sees the back wheels go over the body, so he starts following him,” Scherer said.