Four armed intruders apparently hunting for informants broke into a lightly guarded D.C. prison facility in rural Lorton early yesterday and gunned down a convicted heroin dealer in what law enforcement officials said was a drug-related assassination.

"We're looking for two snitches," the intruders shouted as they lined up several dozen frightened inmates in a minimum-security dormitory. Then Douglas M. Boney, 35, was shot as he attempted to bolt from the building, Assistant U.S. Attorney Karen Tandy said during a bond hearing yesterday for three suspects arrested in the slaying.

Boney, already wounded, struggled out of the building. He was then shot to death "at point-blank range" by one of the assailants, Tandy said.

"This was one of the most brutal vicious attacks I've seen at Lorton," she said.

Law enforcement officials yesterday identified the second inmate sought by the intruders as John D. Irby, a convicted murderer who once worked in a prison work-release program at an auto repair shop owned by Boney's brother, Edward, in Washington.

A brief but massive manhunt followed the predawn attack. Three suspects were apprehended within hours of the shooting. A fourth remained at large last night.

The incident -- which D.C. corrections officials said was the first jail "break-in" they could recall in the area -- also triggered intensive investigations by the FBI and city authorities into circumstances leading to the killing, security at the prison facility and broader implications that the slaying is part of a possible drug war.

Officials in Fairfax County, where the 190-inmate, minimum-security facility is situated 20 miles south of Washington, renewed their complaints about risks to local residents. And prison guard union leaders said recent D.C. Corrections Department budget cuts have left the facility even more vulnerable to intrusion.

The three suspects were charged with first-degree murder in the death of Boney, a longtime Washington resident who had been in and out of prison on an assortment of robbery, narcotics assault and escape charges for the past 15 years.

The three were identified by the FBI as Edward Ford Sharrieff, 32, of 16 S. Van Buren St., Alexandria; Germain P. Stoddard, 24, of 409 Upshur St. NW, and John Elbert Landon, 30, of 4407 Lions St., Marlow Heights.

They were arraigned simultaneously in three separate courtrooms at the U.S. magistrate's office in Alexandria. Sharrieff and Landon were ordered held under $1 million bond each, and Stoddard under $500,000.

Prison, FBI and D.C. police officials gave this account of the attack:

At about 3:15 a.m., four men armed with a shotgun and two pistols entered one of two dormitories at the unfenced minimum security facility. They grabbed two correctional officers as hostages, flicked on the lights and ordered several-dozen inmates out of their beds.

One of the four men was masked. Identifying one another only by the initials "A," "B," "C" and "D," the four intruders said they were "from the mob" and ordered the inmates to form an impromptu lineup.

Boney was not in his assigned bunk area, but moments later one of the intruders spotted him hiding behind some lockers.

The intruders began firing at him. Boney fled from the building, wounded and bleeding. The attackers caught up with him outside and fired again killing him.

The intruders then released the two hostages and fled, abandoning any further effort to find Irby. At least two jumped into a red Pontiac. Officials were not sure whether the others fled on foot or in another car.

Guards alerted Fairfax County police, giving them the tag number of the Pontiac that one of them had noted earlier. About 45 minutes later, county police arrested two men in the car -- Stoddard and Landon -- near the Lorton exit of I-95.

A third suspect, Sharrieff, who was on foot, was arrested about two hours later in the same general area by two D.C. police detectives driving to work, who apparently had heard the lookouts for the suspects on their police radio. They also recovered Sharrieff's 1980 Cadillac nearby on I-95.

Police said they had no leads last night on the whereabouts of the fourth suspect.

Corrections officials said both guard hostages were injured slightly during the attack -- one had a bruised knee, the other a cut leg.

"They apparently got slammed around a little bit," said corrections department spokesman Leroy Anderson.

"They threw me down, and I sprung my knee," said one of the guard hostages who identified himself only as "Bill" during a brief interview outside the facility several hours afterward. He said the intruders had a shotgun and two pistols -- one .38-caliber, the other .25-caliber.

Corrections officials kept reporters out of the immediate dormitory area yesterday as a team of 30 FBI agents interrogated inmates in an attempt to reconstruct the bizarre incident.

In a separate investigation, corrections officials also were looking into whether the facility was adequately staffed and equipped.

Officials acknowledged that three perimeter guards who spotted the red Pontiac at about the time the four intruders entered the dormitory had been unable to alert fellow guards quickly because their car radio did not work.

The guards, according to officials, found the trunk of the Pontiac open and observed a U.S. Army duffle bag inside, containing a box of ammunition and several loose cartridges. The guards jotted down the license tag number of the car and moved on, relaying it later to Fairfax County police after the getaway.

A checkpoint guard at the minimum security prison entrance also saw the four men enter the dormitory from one side of the complex of buildings, officials said.

The guard telephoned the two corrections officers inside the dormitory, officials said, but by then they had already been taken hostage.

"The intruders told (one of the hostages) to answer the phone but just tell 'em everything's cool," one official said.

The minimum-security prison is one of several D.C. correctional facilities in the Lorton area and houses mostly low-risk inmates who are in educational or work-release programs and nearing parole. It has no fences or walls, in contrast to the sprawling medium-security and maximum-security complex housing more than 2,000 inmates a mile or so to the north.

Tandy, the federal prosecutor at the bond hearings yesterday, identified Sharrieff as the suspect who gunned down Boney "at point-blank range."

She said Sharrieff has an arrest record dating back to 1962 and is currently on probation on a drug conviction. In addition, she said, he has been arrested over the years on an assortment of narcotics, arson and assault charges.

For his part, Sharrieff said he has had only two convictions -- one for robbery in 1965 and another for drug possession in 1977 -- but acknowledged he has been arrested numerous times.

Law enforcement officials said late yesterday they are puzzled by the reference to "snitches" attributed to the gunmen.

It is an open secret, they said, that there is a substantial drug operation at Lorton related to any of several competing drug rings on the streets of Washington. Yesterday's raid, they said, rather than being a punishment for so-called "snitches," may have been designed as a show of force by persons seeking a bigger role in the prison drug operation.

The nature of the killing -- four men barging into a prison and shooting a victim -- is odd, law enforcement authorities said, and may have been designed for special effect. It would have been much easier, they said, to shoot Boney while he was out on work release or to have him killed by another inmate rather than risk entering even a minimum security facility.

Irby is considered by law enforcement officials to be one of the main conduits for drug traffic at Lorton. He was indicted four years ago in connection with drug operations there and tried three times.Twice, the case ended in a mistrial and once in a hung jury. Prosecutors reluctantly dropped the charges after the third trial.

Investigators say Irby, Boney and Sharrieff, the principal figures in yesterday's incident, are bound together in a series of loose relationships.

Irby, while a Lorton prisoner some years ago, for example, was on work release assigned to the Washington auto repair shop owned by Boney's brother. It was during this time Irby was charged with selling drugs to an undercover D.C. police officer, leading to the series of Lorton drug mistrials at which he was once represented by attorney P. David Gavin of Washington. Yesterday, Gavin was representing Sharrieff, who was accused of killing Boney and hunting Irby.

Boney was serving a 2-to-6-year sentence for heroin distribution at the time of his death. He was convicted on April 18, 1978 before U.S. District Judge John H. Pratt and sentenced a month later.

Boney's death is the latest in a series of drug-related homicides in the area. On May 15, two men -- Julius Kinard and Cornell Mathis -- were shot and killed in the parking lot of a Roy Rogers restaurant on Georgia Avenue NW near Howard University.

On April 20, Robert L. Blount, was fatally shot by a gunman in a passing car as Blount stood at Fifth and H Streets NE. Police believe all three homicides were drug-related.