A 10-year-old boy was struck by a car and fatally injured last night as he and his father were crossing Connecticut Avenue near their Chevy Chase home. Montgomery County police said the car sped away immediately after the 8:30 p.m. accident and was still being sought early today.

The boy was identified as Jeremy Grodsky, son of Dr. David and Marlene Grodsky, of 7317 Maple Ave. Police said he was pronounced dead of head and internal injuries at 10:20 p.m. last night at Suburban Hospital.

A relative said late last night that Jeremy, a third-grade pupil at Chevy Chase Elementary School, had been attending a cub scout meeting with his father at the Chevy Chase United Methodist Church at 7001 connecticut Ave.

As they crossed the southbound lane of Connecticut Avenue after the meeting, the relative said, Jeremy lagged a short distance behind his father and was struck by a speeding, dark green auto.

David Grodsky, a psychiatrist, ran back by his son and began administering mouth-to-mouth resusciation. Several motorists stopped their cars and directed traffic around the father and son until police and an ambulance arrived about 10 minutes later.

The boy was taken to Suburban Hospital, where he died about two hours later, police said.