Six members of a newly-formed Virginia motorcycle gang called "The Invaders" were found shot to death Friday night in a suburban Richmond home in what police described as one of the worst mass murders in the state's recent history.

The victims -- four men and two women -- each had been shot in the head and were discovered in five different rooms at the small frame home, located in a working-class neighborhood, just south of the Richmond city limits.

"It's the first time in the history of the county that we've had anything like this," said Chestefield County Police Lt. Herbert M. Shelton. "I've worked here for 20 years and there has never been anything comparable."

County police, joined by a team of federal firearms investigators and FBI agents, said they were at a loss to explain the killings of people neighbors said they knew only by nicknames like "Snake" and "Wild Willie." One officer speculated last night that one of the victims may have killed the five others and then committed suicide.

"We don't know why it happened yet," said Lacey Campbell, a supervisor for the federal Alcohol, Tobacco, and Firearms Division in Richmond. "Everything is very fragmented right now."

Several firearms and some drugs were discovered inside the home, according to police, but none of the weapons were believed to have been used in the killings. Officers were baffled how six people were killed without neighbors hearing shots and one detective said the officers were assuming that the victims could have been under the influence of drugs when they were shot.

Neighbors said as many as 12 people have lived in the small home and police said the gang had not had nay confrontations with authorities or others in the community. "So many people come and go from there that no one really pays any attention," said Shelley Collingsworth, one of the residents of the area.

"I've been expecting something to happen there," said James E. Evans, who lives right across the street. "They stayed up all night, playing poker and running motorcycles. If they haven't been in trouble then I don't know who has. The last thing I heard over there were some motorcycles rolling out at 1 a.m. Thursday . . . but that was just nat'ral for them."

The victims were identified by police yesterday as David E. Boaze, 33, a Richmond mechanic; his girlfriend Pamela S. Miller, 24; Steve Smith, 39, a part-time mechanic; David Wayne Waldrop, 26; Gerald L. Brickhouse, 21; and Krisiti Lynn Myers, 18.

Investigators speculated yesterday that the gang members, who were killed with a small caliber weapon, had probably been dead for two days.

The six victims had been expected to attend a Wednesday night meeting of The Invaders, formed in October, in another section of Chesterfield County, according to investigator Shelton. When none of the six showed up, Daniel Trevillian of Richmond, a gang member, telephoned the home where the bodies were found and received non answer, police said.

On Friday night, Trevillian went to the home and immediately became suspicious when he found a garage door unlocked and all six of the victims' motorcycles inside, police said.

When Trevillian glanced through a front window, he saw the first body and called police. "There was one female on the living room-dining room floor. There was another male and female on the kitchen floor. There was a male victim in each of the two bedrooms, and another male found in the bathroom," Shelton said.

There was no sign of forced entry to the home, and no evidence of any kind of struggle. None of the rooms had been ransacked. No chairs or tables had been overturned -- all unusual facts since investigators are at a loss to determine how six victims could have been shot without being alerted by the gunfire. None of the victims had been bound, gagged or beaten, and though nearby homes were less than 60 feet away, neighbors reported hearing no gunshots, said police.

"After awhile, you just try to ignore what goes on there," said Collingsworth, the neighbor. "There would be loud noises at night and them revving those bikes, but no one was crazy enough to go over there and tell them to stop."

Motorcycle gang violence has become a rarity in the Richmond area in the past decade and arrests have decimated the ranks of most local gangs, say police. Although membership figures for The Invaders are unknown, some Richmond investigators said that their formation may be part of a resurgence of gang activity. Other gangs were reportedly envious of The Invaders because of their relatively clean record with local police.

Shelton said that extensive interviews with gang members had turned up no motive for the slayings.