Four Washington-area residents were fatally injured in unrelated traffic accidents here yesterday morning, authorities reported.

An 18-year-old Fairfax County man was fatally injured while riding in a pickup truck that went out of control and crashed into a tree on Valley View Drive in Franconia, Va., Fairfax County police reported. Police said Richard L. Johnson of 6208 Marilyn Dr. was thrown from the truck during the accident and pronounced dead at the scene.

The driver, David M. Kennedy, 21, of 6203 Marilyn Dr., was treated for minor injuries at Fairfax Hospital and released.

In Forestville, 23-year-old Willie B. Holbrook of Southeast Washington was also killed early yesterday when the motorcycle he was driving struck the back of a moving auto at Pennsylvania and Shady Side avenues, Maryland state police said. They said Holbrook was thrown 117 feet from the vehicle.

A third victim, identified as Kathleen Kelly, 24, of Baltimore, was fatally injured when the car she was driving on I-95 in Laurel went off the main roadway, struck an unoccupied truck and rolled into a ditch. A passenger in her auto, Patricia Ann Lawrence, 25, also of Baltimore, was seriously injured in the crash, police said.

And in another early morning accident in Prince George's County, 19-year-old Joey Hodge of Waldorf was killed when his car went out of control on Rte. 301 in Brandywine and crashed into several trees, police said.