An experienced 31-year-old runner collapsed less than 150 yards from the finish line of the Army 10 Miler road race yesterday and died a short time later.

Army Capt. Ron Gilliard, who lived in Alexandria and worked in the Office of the Inspector General, was nearing the finish line about one hour after the start of the race -- which placed him among the fastest of the 6,000 entrants -- when he collapsed and fell in the roadway in front of the North Parking lot of the Pentagon in full view of hundreds of spectators.

He was flown by helicopter to MedSTAR at the Washington Hospital Center, and he was pronounced dead at 10:27 a.m., according to the hospital. The cause of death will not be determined until the completion of an autopsy, which should take about a week according to hospital spokeswoman Clare Fiore.

"There are a large variety of cardiac abnormalities that are known in lay terms as athlete's heart that go undetected and can cause sudden death," said Fiore. "We wouldn't want to speculate at this time."

Daniel Herr, the Associate Medical Director of MedSTAR, attempted to revive Gilliard at the hospital, and Fiore said a medical team treated the stricken runner for more than 30 minutes. Herr was not available to comment.

Bystanders at the race attempted basic first aid on Gilliard, and some doused their shirts in the Potomac and wrapped him in the wet clothing to help lower his body temperature. Raymond Phillips, a physician who was running behind Gilliard, administered CPR "probably within a minute or two," after Gilliard went down, he said. "There were only three or four people around him."

"I don't know what happened, he just collapsed," said Phillips. "I did CPR. There was no pulse. . . . There was no activity by his heart."

Gilliard was among a crowd running in the range of six-minute miles. The roadway was jammed by a solid block of runners from where he fell to the finish line.

Before Phillips arrived to administer CPR, an unidentified nurse who was in the crowd was assisting the fallen runner. Shortly after she began trying to help him, a medic assigned to the race arrived on the scene, according to the race director, Maj. Larry Cerrutti. "I reviewed medical plans before the race and we had three doctors, 40 medically trained technicians and there's not a whole lot more you can do," he said.

"In a race like this, unless you have a medic every 30 feet, there'll be some time in responding. Unless you have medics running in the race with backpacks, you can't get to them any sooner. I think we have sufficient medical coverage in this race."

The weather conditions -- sunny, low seventies and 50 percent humidity -- are considered hot for a long-distance race. Four years ago in slightly cooler weather, a 32-year-old Marine staff sergeant died of heart-related problems 15 miles into the Marine Corps Marathon.

For the Army 10 Miler, which goes from the Pentagon, across Memorial Bridge, through West and East Potomac Parks and back to the Pentagon across the 14th Street bridge, Cerrutti said there are three ambulances parked along the course and one mobile ambulance trailing the last runner. There is a medical aid tent at the finish line. Ambulances and medical teams are prepared to respond to radio calls.

"In this case, where a runner went down, we dispatched a mini-ambulance, an electric cart and he brought with him the life pack and the fibulators. The technician determined the severity and brought in the ground ambulance. They called in one of the life flights {a helicopter} and he was sitting on the ground for 15 minutes before they were ready to transport him. We pre-informed Arlington Hospital and George Washington Hospital in the event of need before the race.

"The medic I personally dispatched -- the fellow took off while they were loading the mini-ambulance -- got there as the nurse was working."

Officials at the race said Gilliard was a seasoned runner and trained eight to 10 miles a day. But, said Cerrutti, "He was flat-lining {no heartbeat} when {the helicopter} lifted off."

"He was in excellent condition; it was something massive," said Medic Staff Sgt. Carl Berry, who accompanied Gilliard to the hospital. "Something erupted, it just went out. A P.E. {pulmonary embolism} is the only thing they {attending doctors} figure might have happened to him. Little or no oxygen was getting through."