A 21-year-old Maryland state trooper was critically injured and a 19-year-old Silver Spring woman was killed yesterday following an accident on the beltway just east of the Georgia Avenue exit, state police report.

Police said Tropper Leonard F. Glenn, of the Rockville barracks, had stopped to assist two motorcyclists and their two passengers after they stopped on the shoulder of the beltway at approximately 2:30 a.m. Police said moments later, a 16-foot moving van plowed through the group of five persons.

Sallie Hoopes, of 1909 Powder Mill Rd., was killed at the scene and later pronounced dead at Holy Cross Hospital. Tropper Glenn was flown by Maryland state police helicopter to the shock trauma center at University Hospital in Baltimore. Another cyclist, Gerd Heinsohn, 21, of 11221 South Glen Rd., Potomac, was astride one of the cycles, but was not seriously injured.

The trucker who allegedly plowed into the group, Richard T. May, 30, of 1507 Farsta Ct., Reston, told police he did not see the five persons in the road, police said.

According to police, the trucker notified state police about the incident by calling on the trooper's police radio.

Police said May has been charged with failure to drive in a single lane and negligent driving, pending additional investigation.

In a traffic accident that occurred an bour earlier, a 19-year-old Rockville man was killed when his motorcycle went out of control and he left the roadway and struck a power pole.

Jeffery J. Gergens, of 5129 Glavel Ter., was killed as he traveled eastbound on Redland Road near Panorama Drive, Montgomery County police said. He was taken to Suburban Hospital where he was pronounced dead at 2:40 a.m.

In another accident, a Baltimore man and woman were killed and three other persons were seriously injured when a car they were riding in went of control, struck a guard rail and burst into flames on the Baltimore-Washington Parkway at the Beltway early yesterday morning, police said.

Killed were: William R. Mc Niel, 20 and Monica Hodges, 19. The other passengers in the car were thrown from the vehicle and were taken to Doctor's Hospital in Lanham, police said. They were in serious condition yesterday, a hospital spokesman said.

Police said they had not yet determined why the vehicle went out of control.