A Silver Spring fireman was killed and a volunteer firefighter seriously injured early yesterday when the ambulance they were riding in was struck by a car at the intersection of Old Georgetown Road and Democracy Boulevard in Bethesda, Montgomery County police reported. The ambulance was transporting an accident victim to hospital.

Montgomery police said the ambulance, with its siren blaring and its red lights flashing, was traveling south on Old Georgetown Road when it was hit broadside by a vehicle operated by Hella Von Sampson, 40, of 6004 Chatsworth La., Bethesda. The ambulance was turned on its side.

Police said Von Sampson failed to stop for the speeding ambulance as she entered the intersection from the Georgetown Square Shopping Center.

Von Sampson, a researcher for the Library of Congress, was charged with vehicular manslaughter, driving while intoxicated and failing to grant the right of way to an emergency vehicle, police said. The ambulance was operated by the Rockville Fire Department, according to police.

James Stuart Nicewarner, 23, of 11602 Gall Pl., Silver Spring, a firefighter who volunteered his time as a paramedic, died as a result of multiple internal injuries suffered in the crash. He had been riding in the rear of the ambulance, police said.

Fire officials said Nicewarner and another paramedic were called out around 1:15 a.m. to transport a man injured in an accident at Rockville Pike and Nicholson Lane to Suburban Hospital.

Police said the injured man, James Keller, 32, of 17800 Trundle Rd., Dickerson, had been driving along Rockville Pike with his car headlights off when he crashed into a traffic light pole in the center island.

Keller was listed in stable condition yesterday after being transferred from Suburban to the intensive care unit at Washington Hospital Center. The extent of any injuries suffered as a result of the second crash could not be determined.

Also injured in the ambulance accident was Marshall Smith, 27, a volunteer firefighter from Laytonsville, who was riding in the rear of the ambulance with the patient and Nicewarner. Smith, who suffered leg injuries after being pinned in the rear of the vehicle, was listed in stable condition yesterday at Suburban.

Stephen Proctor, 18, of 16009 Wallingford Rd., Wheaton, the ambulance driver and a member of the Sandy Spring Volunteer Fire Department, was treated for minor injuries at Suburban and released, police said.

Von Sampson referred all inquiries about the accident to her lawyer, saying, "My feelings are endless in this particular case . . . I have extremely deep feelings about what happened."

"She's just very sorry it happened," said Von Sampson's lawyer, Thomas Meehan.

Nicewarner, who would have turned 24 Tuesday, had done fire and rescue work as a volunteer in Silver Spring for two years before joining the Silver Spring Fire Department in 1975. Trained as an advanced paramedic, he held college degrees in fire science and electrical engineering and was completing courses in fire protection engineering at the University of Maryland, according to fire department spokesman Lt. Leonard King.

He lived with his parents, Walter and Virginia Nicewarner, in Silver Spring.

Smith works as a computer research manager for Com-Ten in Gaithersburg and, like Nicewarner, was volunteering his time as a paramedic.

King called Nicewarner and Smith "very dedicated men who put an awful lot of time" into fire and rescue work.