The incident began about 7:40 a.m. yesterday, when a passer-by called 911 to report a man walking down Fall Hill Avenue near Canal Street wearing only a T-shirt, underwear and one sock.

Fredericksburg police determined that the man needed medical care. A rescue crew worried he might have hypothermia on the cold and rainy day, said Fredericksburg Fire Department spokesman Reggie Phillips.

He was wheeled into the hospital on a stretcher about 8:10 a.m. While in the patient registry area, he got up and ran to the ambulance, which was still running, Phillips said. Paramedics called for help.

The driver lost control of the ambulance near Walker-Grant Middle School. The vehicle flipped several times and ended up on the southbound road--in Spotsylvania County just past the city line--about 8:20 a.m.

Shelhorse said the driver apparently was ejected from the car through the windshield or side window. Bleeding, he ran from police, who caught him a short distance away near a car-rental business.