Raleigh, N.C. — The driver of a Greyhound bus that rear-ended a flatbed truck Wednesday morning and flipped along U.S. Highway 1 in Vance County had been convicted twice of speeding.

Nearly 50 passengers were taken to local hospitals after the bus collided with the tractor-trailer at Raleigh Road and U.S. 1 south of Henderson.

The North Carolina Highway Patrol said the bus failed to slow down when the truck slowed to make a left turn. The bus hit the truck, then ran off the road and down and embankment before rolling onto its side.

The bus driver, Keith Lamont Small, 62, of Durham, and passenger Effie Peguef were listed in critical condition at UNC Hospitals in Chapel Hill Thursday afternoon.

Some passengers questioned whether Small fell asleep at the wheel.

Trooper James Montgomery of the state Highway Patrol said the truck driver wasn't at fault in the wreck, but no charges have been filed yet against Small because of his condition.

Court records show that Small was convicted of speeding in Durham County in 2002 and in Rowan County in 2001. It was unclear whether he was driving a bus in either of those incidents.

Forty-nine bus passengers were taken to Maria Parham Hospital in Henderson, where they were treated and released.

The driver of the tractor-trailer, Gregory Jefferson, of Henderson, and his passenger, Angela Lynette Williams, 34, of Henderson, weren't injured.

The bus was being operated by Carolina Trailways, a subsidiary of Greyhound, and was traveling from Richmond, Va., to Raleigh.