A tractor-trailer carrying bags of cement hit and killed an 8-year-old boy Monday afternoon in Kershaw County.

The boy was hit soon after stepping off a school bus around 3:15 p.m. on Sessions Road.

The boy’s 7-year-old sister, 14 other Blaney Elementary school kids and the bus driver witnessed the accident, Kershaw County Sheriff Steve McCaskill said.

Authorities have not released the boy’s name.

“He didn’t know what hit him,” McCaskill.

The bus had been parked in the right-hand lane, and the boy had just stepped off. He had crossed in front of it to the left-hand lane when the accident happened.

“The truck was coming around the corner and couldn’t stop in time,” McCaskill said. “(The driver) tried to go around the bus rather than hit it and hit the child instead.”

The boy fell in the middle of the road, McCaskill said. His sister had been behind him.

Forty-six-year-old Sylvester Williams, of Elgin, faces charges of unlawful passing of a stopped school bus with fatality. Williams is being held at the Kershaw County Detention Center.

Williams was driving for Santee Carriers of Holly Hill.

The State Highway Patrol Department is investigating whether Williams was speeding.