HENDERSON, N.C. --

A Greyhound bus slammed into a tractor-trailer Wednesday and plunged down an embankment, injuring about 50 people, officials said.

At least two people were critically injured and airlifted to UNC Hospitals in Chapel Hill, said hospital spokeswoman Stephanie Crayton.

The bus was traveling from Richmond, Va., to Raleigh on U.S. 1 when a tractor-trailer ahead of it made a turn and the bus failed to slow down, said Sgt. Steve Green, a spokesman for the North Carolina Highway Patrol.

After hitting the truck, the bus ran off the shoulder and down an embankment, tipping on its side, Green said.

Maria Parham Medical Center in Henderson was treating 49 patients though none appeared to be critically hurt, said hospital spokesman David Ruggles.

"We have no serious, life-threatening injuries - mostly bumps and bruises and broken bones," Ruggles said.

The bus driver was among the injured, while the truck driver was not hurt, Green said. The accident happened near Henderson in north-central North Carolina.