At least 50 people were taken to hospitals Wednesday, including two in critical condition, after a Greyhound bus collided with a tractor-trailer and overturned near Henderson, hospital and Highway Patrol officials said.

The bus driver was airlifted to a hospital but the severity of the injuries wasn't clear, said Sgt. Steve Green, a patrol spokesman. He said the driver of the tractor-trailer wasn't injured.

UNC Hospitals spokeswoman Stephanie Crayton said two people in critical condition were airlifted to the Chapel Hill hospital, but it was unclear whether one was the bus driver.

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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.

Green said the bus was traveling southbound behind the tractor-trailer on U.S. 1 near Henderson on Wednesday morning when it failed to slow down as the truck made a left turn. The bus collided with the tractor-trailer, ran off the right shoulder and down an embankment before tipping onto its side.

Green said the bus was traveling from Richmond, Va. to Raleigh. Both southbound lanes of U.S. 1 are closed.

Henderson is about 45 miles north of Raleigh.