A Washington woman and a Silver Spring man were killed in separate Montgomery County traffic accidents yesterday, one an hour after midnight and the other an hour before dawn, police reported.

Investigators said the first accident occurred about 1 a.m. in the 13000 block of River Road in Potomac when a man from Hollywood, Cal., crossed the center line in his 1985 Buick Century and hit a Honda CRX head-on.

The driver of the Honda, identified by police as Isabel M. Duarte, 21, of the 2300 block of Tracy Place in Northwest Washington, died from head injuries, investigators said.

Phill Lewis, identified as the Buick's 23-year-old driver, was taken to Suburban Hospital in Bethesda where he was listed yesterday in fair condition.

Charges were pending in the case last night.

The second Montgomery County accident, in which a pickup truck ran into the back of a garbage truck near White Oak, occurred at 6:25 a.m.

Police said Jerome Patrick Walsh drove his 1986 Toyota truck into the back of a truck that empties large trash containers.

The 30-year-old Silver Spring man, who was declared dead at the scene, had been driving north in the 12000 block of New Hampshire Avenue when he hit the truck.

Police said the driver of the garbage truck, Lacy Junior Maccraw, 40, of Baltimore complained of neck injuries.