A holdup suspect bleeding from police gunfire was apprehended in downtown Bethesda yesterday after leaping into the back seat of a moving red convertible, ending an incident in which a police officer was stabbed and a 12-year-old girl was knocked unconscious, police reported.

The unidentified suspect, shot once in the abdomen, was reported in critical condition at Suburban Hospital.

The chain of events started shortly after 3 p.m. when a man with a knife robbed the Silver Tray convenience store in the 7500 block of Old Georgetown Road, police said. Before fleeing with an undisclosed amount of cash, the man smashed a glass bottle over the head of a 12-year-old girl who was minding the store while her parents ran an errand, police said.

Customers found the unconscious girl lying on the floor and called the police, said police spokesman George Ludington. The girl was treated at Suburban Hospital and released, he said.

After police broadcast a lookout for the robbery suspect, Ludington said, Officer Kevin E. Pugh saw a man fitting the description at Elm Street and Wisconsin Avenue, about two blocks away. When Pugh confronted the man, the officer was attacked with a kitchen knife, wounded in the hand and knocked to the ground, Ludington said.

Pugh fired several shots at the suspect, hitting him once, Ludington said. The wounded man then ran a block or two to Hampden Lane, where he spotted a 20-year-old red Camaro convertible headed east in the 4700 block near a parking garage.

Police said the man dived into the rear seat of the slowly moving car, startling the driver, David K. Berler, a Chevy Chase ophthalmologist. Berler, dressed in tennis whites, appeared unfazed later when talking to reporters about the encounter.

"I saw this man face down on the back seat of the car," Berler said later. "Obviously he had been shot. There was blood on the interior of the car." Berler slammed on the brakes, and seconds later, Pugh and another officer arrived and arrested the wounded man, Ludington said.

Pugh, a 5 1/2-year member of the force who is a motorcycle officer at the Bethesda police station, was treated at Suburban and released, then placed on "traumatic incident" leave, police said. Ludington said there were no bystanders in the area when Pugh fired at the suspect.

Yesterday's shooting was the second in a dozen weeks in the congested Bethesda business district. On June 16, Vahag Babayan, a Bethesda jeweler, shot and killed two suspected holdup men after a robbery at his store in an arcade between Wisconsin and Woodmont avenues. Babayan was indicted last month on murder charges.