Rescue workers from special Fairfax County cave-in teams toiled for three hours yesterday outside a lube shop in Annandale before safely extracting two men who were pinned against the wall of a trench as they were preparing to install an oil tank.

Donald Klinger, 30, of Annandale and John Houff, 22, of Woodbridge were taken to Fairfax Hospital, which had been monitoring their vital signs by two-way radio reports from the beginning of the massive rescue effort a few miles away. Klinger was listed in good condition with knee injuries and Houff was reported in fair condition with pelvic injuries.

As the rescue operation progressed, blood samples were taken from the men and rushed to the hospital for analysis. Long before the men were extricated, word came from the hospital that abnormalities had been detected in the blood and fluids were administered intravenously to correct chemical imbalances.

Managers at the Jiffy Lube at 4301 Backlick Rd. said the men were installing the oil tank when the cave-in occurred about 11:15 a.m. They said the workers, employed by the York Service Co., had discovered an old oil tank when they were digging the hole, had removed it and were smoothing the bottom when one side of the eight-foot-deep trench collapsed.

"I tried to dig them out," said assistant manager Gary Williams, 24, who jumped in the 6-by-20-foot hole. "They were screaming and hollering . . . . Both of their legs were pinned in."

It was the first major challenge for Fairfax County's two new cave-in units, which began operating in June.

Much of the rescue effort involved shoring the inside of the trench to prevent further collapse, a task that was complicated by the mixture of clay, asphalt and concrete.

"We used our own shoring materials," said Assistant Fire Chief Glenn Gaines. "There weren't any here."

Any trench deeper than five feet is required by law to be shored, but Gaines said that "for some reason they went in," even though the trench lacked shoring. Ed Hill, a Virginia compliance safety and health officer, was on the scene and said he will submit a report.

"This wouldn't have happened if the the trench was shored initially," said Donald Deskins, 38, one of those in the Fairfax Fire and Rescue Department who has had special training for the new cave-in units. "But it's common to find somebody working in an unshored trench."

Deskins said the workers were using state-of-the-art rescue equipment, including specially treated wood and gas-filled metal pipes, called air shores, attached to the wood to keep the sides of the trench from collapsing.

Ed Healy, 30, one of the cardiac care technicians who went into the hole, said the workers, who were buried up to their chests, had to be completely freed before they could be lifted out. "If the dirt is just over your ankles, we couldn't bring you out," he said.

Deskins explained that one square foot of dirt can exert 700 pounds of pressure.

Healy took the blood samples that were relayed to the hospital.

Houff was the first to be extracted from the trench, his stretcher carefully lifted with ropes. When Klinger was slipped into an ambulance, the crowd that had gathered erupted into applause.

Injuries and fatalities on Northern Virginia construction sites prompted concerned county officials to allocate funds last year to establish the cave-in rescue units.

Fire officials are now discussing the possibility of making the teams available internationally, a spokesman said, "so if there's another Mexico City, they could possibly call Fairfax County."