A school bus Monday ran over and killed a kindergarten student who had just stepped off the vehicle, police said.

The bus driver had stopped to let some children off, drove on and felt a bump under the bus, police spokesman Officer Ron Reier (search) said. Thinking it was a backpack, she drove a little farther and saw the boy's body in her rearview mirror, he said.

Police were interviewing the driver and planned to do drug and alcohol tests, he said.

The names of the boy and the driver were not immediately released.

Broadcast reports identified the boy as Kong Meng Vang (search), and said he arrived from Thailand with his mother and eight siblings about six months ago. His father had died in Thailand (search).

"She can't believe that her son just passed away. She still thinks he's alive," said Lao Moua, who works in the area and notified the mother.

The child's uncle, Lea Vang, said the boy's mother blamed herself because she usually comes to the bus stop to pick up her child.