Douglas B. McMillan, a 34-year-old former Marine from Alexandria, was making his rounds as part of the U.S. Capitol Police "first responder unit" when a deranged gunman burst through a metal detector at a Capitol entrance and shot fellow officer Jacob J. Chestnut in the head.

McMillan, who happened to be nearby, drew his 9mm Smith & Wesson semiautomatic and exchanged fire with the gunman, wounding him and preventing him from going into a part of the building where "hundreds of members of Congress, congressional staff and visitors would have been potential targets," according to a Capitol Police citation. "He also prevented the gunman from shooting several witnesses who were in the immediate area."

McMillan, a three-year member of the Capitol force, who was not wounded in the July 24, 1998, attack, is one of 14 federal law enforcement officers to be honored tonight when the Federal Law Enforcement Officers Association hands out its annual awards for heroism and bravery at a banquet in Arlington.

Receiving the organization's highest award posthumously are Chestnut and Capitol Police Special Agent John M. Gibson, who also was killed in the attack on the Capitol. Russell Eugene Weston Jr., a former mental patient from Montana, has been indicted on two counts of murder and other charges in the attack.

Although the sacrifices of Chestnut and Gibson are well known, the actions of other federal law enforcement officers receiving awards have drawn far less attention. For the association, whose members include more than half the 31,000 U.S. federal agents assigned worldwide, tonight's ceremony is an occasion to recognize some unsung heroes and recount cases that have remained largely out of the spotlight.

"Many of the award winners I speak to view this recognition by their fellow agents as greater than a commendation letter," said Michael Prout, the association's national awards director and a senior inspector in the U.S. Marshals Service.

Attorney General Janet Reno is scheduled to address the group and present medals to the recipients from the Capitol Police, the State Department's Diplomatic Security Service, the U.S. Customs Service and the Drug Enforcement Administration.

McMillan, who previously served as a special deputy U.S. marshal, could not be interviewed on orders of the Capitol Police and government prosecutors because he is a witness in the case against Weston. He is on assignment in Mississippi and will not personally receive his medal, said Lt. Dan Nichols, a Capitol Police spokesman.

The award citation offers a few new details of last year's incident but leaves other aspects unclear. McMillan "shot the suspect several times," the citation says, diverting him from a path that could have led to even greater bloodshed.

"When Doug engaged the gunman, it forced him down a certain corridor instead of allowing him to go deeper into the building," Nichols said. He declined to say how many times or where McMillan had shot the gunman, who was finally stopped in an exchange of fire with Gibson.

Among the other honorees are three special agents of the Diplomatic Security Service, which helps protect U.S. embassies abroad, guards State Department officials and investigates fraud involving U.S. passports and visas. Paul Peterson, Robert Simons and John Kane were cited for heroism for securing the U.S. Embassy in Nairobi after it was bombed last year by terrorists and for safely evacuating injured and traumatized staff members.

"The interior of the embassy was a deathtrap," with high-voltage wires dangling throughout and walls crumbling, an award citation says. Fire raged over a 30,000-liter tank of diesel fuel, emitting toxic gases from burning plastic.

The three officers worked without rest for two days to try to rescue survivors, digging through rubble by hand and keeping looters out of the site until they were relieved by U.S. Marines.

"We weren't sure if the building would stay up or not," said Peterson, 46, who had taken over as the embassy's regional security officer just 19 days before the bombing. "In the first six hours, we removed a lot of wounded."

Michael Bayer, 38, another diplomatic security agent, won a separate investigative award for breaking up a ring that smuggled Czech women to New York and forced them to work in Times Square peep shows. "We do some really good work that is pretty much unheralded," Bayer said.

Receiving the association's second-highest award, for bravery, are six Customs Service pilots and two DEA agents. The pilots mounted a daring rescue attempt in shark-infested waters in the Caribbean last year when a Customs plane was forced to ditch after a collision. One injured pilot in the stricken plane was saved, but another perished.

The DEA agents, Joseph Giuffre II and William C. Athas, hacked their way through dense tropical forest in the Bahamas last year to rescue two U.S. Army pilots and a crew chief whose helicopter crashed on a flight related to a drug enforcement operation.

CAPTION: Paul Peterson, security officer, will be honored for his actions after the bombing of the U.S. Embassy in Nairobi.

CAPTION: Officer Douglas B. McMillan wounded suspect in Capitol killings.