A 6-year-old boy, injured yesterday when a school bus swerved onto a sidewalk in Foster Village, was in guarded condition last night at The Queen's Medical Center.

The incident happened at 11:20 a.m. near Bougainville and Haloa drives, and involved a Roberts Hawaii bus.

The boy reportedly was walking with two other children on the sidewalk when the incident occurred. The youth suffered serious head injuries, said city Emergency Medical Services spokesman Bryan Cheplic.

The other children were not injured.

Officers from the Kalihi police patrol district filed a report on the incident indicating the child was hurt when the bus grazed him.

But Roberts Hawaii, a contractor which provides school-bus service, issued a statement saying its investigators determined the boy fell while running and was not struck by the bus or by a utility pole that fell after being struck by the bus.

Company spokesman Wally Zimmermann said an aide and driver were the only people aboard the bus, which was returning to the company's Sand Island base yard when the accident happened.

The bus unexpectedly swerved to the right for unknown reasons, Zimmermann said.

"(Roberts Hawaii mechanics) don't know what made the bus swerve to the right, jump the curb and hit a telephone pole," Zimmermann said.

"Witnesses interviewed by Roberts Hawaii investigators said the kid was running, fell and injured himself."

The driver and aide were not injured. The driver was subjected to a post-accident investigation and was found not to be impaired in any way, Zimmermann said.

Reach Rod Ohira at rohira@honoluluadvertiser.com.