The first ambulance hijacking in Prince George's County ended peacefully yesterday when the hijacker surrendered to the police after the two volunteer fireman manning the ambulance escaped.

Barry Beauchamp and Kenneth Roach, manning Ambulance No. 348, left the Adelpi-Chillum Prince George's County fire station at 3:41 yesterday on what they thought was a routine pickup. A man had been reported sick at 7900 New Riggs Rd. in Adelphi.

Arriving at the address, they assisted an apparently weakened 21-year-old patient into the ambulance and headed towards Washington Adventist Hospital in Takoma Park.

Beauchamp was behind the wheel and Roach was in the rear with the patient. During the ride, the passenger pulled a handgun on Roach, according to police. As Beauchamp drove through the hospital gate, he told the Takoma Park city police by radio that he and his partner were being held at gunpoint.

At that point,the patient ordered Beauchamp to turn the ambulance aroundand drive back to the house where he had been picked up. Beauchamp began driving along University Boulevard with four Takoma Park police cars in pursuit. After driving about six blocks he intentionally turned down a dead end street, police said, stopping at a retaining wall.

Beauchamp then jumped from the ambulance and ran.

The patient, according to the police, followed, still holding Roach at gunpoint.

But when the gunman turned to try to grab the fleeing Beauchamp, Roach pulled free and took cover. The patient then surrendered to police who had pulled up behind him. Police identified the man as Richard Lam of no fixedaddress.

Lam was charged with two counts of kidnaping and use of a handgun.