Four Montgomery County policemen have been placed on administrative leave as a result of an incident Saturday afternoon in which two of them killed a gun-wielding Wheaton man in the front yard of his home.

The slain man, 32-year-old Robert V. Williams of 3415 Embry St., was shot three times in the chest by Sgt. Ted Parker Jr. and Officer William S. Issacs Jr., who reported that Williams had threatened them with his rifle. The officers were called to a house next door to Williams' after police received a telephone call from someone reporting that a man was brandishing a gun. It turned out, police said later, that the person who made the call was Williams.

The first officers on the scene were Timothy Delaney, who was off duty, and Bryan McManus. According to police, as those two officers approached the house next door, Williams stepped from his front porch carrying a rifle. Police said Williams then ordered the officers to throw down their guns. The two officers then fell to the ground on the lawn next door to Williams.'

Sgt. Parker and Officer Issacs then arrived outside Williams' house. When Williams pointed his rifle at them, police said, both Issacs and Parker fired their shotguns, fatally wounding Williams, who had not fired any shots from his rifle.

Police information officer Nancy Moses said yesterday that the first two officers on the scene relayed a radio message to Parker and Issacs that they were pinned down. When Parker and Issacs arrived at the scene, Moses said, they saw the two officers on the ground. "The man with the rifle turned to them, confronting them with a rifle," Moses said. "He said something unintelligible. It was a life-threatening situation."

The police department's internal affairs division and crimes against persons division are conducting investigations of the shooting. The results of these investigations will be turned over to a grand jury.

Williams, an independent newspaper distributor of The Washington Post, attended the funeral of a nephew on Saturday a few hours before the 3:30 p.m. confrontation with the police. When he arrived home from the funeral, according to his father-in-law, Philip Manson, Williams was angry and "began throwing things around."

A short time later, Williams' nextdoor neighbor, Sandy Dae, 13, overheard Williams telling police on the telephone that there was a gunman in her house. "Our door was open and his window was open, so I could just hear it," Dae said. "I was curious why he said our address."