Investigators say they plan to check if mechanical error could have caused a school bus carrying a dozen children to crash into a house in South Oakland.

The bus was carrying students of the Renaissance Academy of Pittsburgh Alternate of Hope, a charter school based in East Liberty, when it drove off a hillside on Swinburne Street around 7:30 a.m.

Four children on the bus were taken to Children’s Hospital with relatively minor injuries.

State Police told KDKA that Mill Transportation, the company that owns the bus, has a pretty good record. The bus involved in the crash was inspected August 10 and was in good condition.

“It could have been driver error or vehicle error. We don’t know at this time,” said Sgt. Rich Begenwald of Pittsburgh Police.

Meanwhile, pulling his oxygen tank and using a cane, Charles Haynie, 89, returned to his crumbled home this afternoon, where he was abruptly awakened this morning.

Haynie’s house, where he lived for 50 years, will be torn down. He says he will live in an apartment nearby until he finds permanent housing.

“I’m thankful no one got hurt. There were 12 kids on a bus. And that driver, I don’t know. [He] must have had a seizure or something,” Haynie said.

Eyewitness Robby George told KDKA’s Mary Robb Jackson the driver didn’t make any mention of a medical problem.

“He said that his foot slipped. But when we told the cops what the driver said, he told them that … there was something wrong with the steering,” George said.