According to the Highway Patrol, the driver ran off the right side of the road and overcorrected, causing the ambulance to leave the road and flip over on its side.
Witnesses say the ambulance was not speeding, and did not have its lights and sirens on at the time of the accident.
The two EMTs riding in the front of the ambulance had to be extricated from the vehicle, while the other two people on board were helped out by responding emergency workers.
All four were transported to UNC Hospital in Chapel Hill with injuries that are not considered to be life threatening.
The driver of the ambulance was cited for failing to maintain lane control.