Relatives of two Washington area sniper victims plan to file suit today against the gun manufacturer and the gun shop linked to the Bushmaster XM15 assault rifle used in the shootings that terrorized the region last fall.

The families of sniper victims James L. "Sonny" Buchanan and Conrad Johnson allege that the companies showed "gross negligence" that "caused injuries and death," according to a draft of the suit provided yesterday. The plaintiffs, represented by the Brady Center to Prevent Gun Violence, will outline allegations at a news conference today.

The suit is to be filed in Washington state against Bull's Eye Shooter Supply of Tacoma, which either sold or lost the rifle in a theft; Brian D. Borgelt and Charles N. Carr, owners of the gun shop; Bushmaster Firearms Inc. of Windham, Maine, maker of the gun; and sniper suspects John Allen Muhammad and John Lee Malvo. The families are seeking unspecified damages.

"I hope ultimately there will be control over who obtains firearms," said Vickie Snyder of Rockville, the sister of Buchanan, a 39-year-old landscaper who was killed Oct. 3 while mowing grass at a car dealership near White Flint Mall. "I guess I really hope the shops will be more responsible in their paperwork and the manufacturers will be more responsible about who they sell guns to."

The other family in the case is representing Johnson, 35, a Ride On bus driver who was slain Oct. 22 in Aspen Hill.

Dennis Henigan, legal director of the Brady Center, said that at least three more families of sniper victims plan to join the suit soon.

The organization has filed more than two dozen similar suits on behalf of municipalities and individuals.

"This assault rifle, which served the snipers' deadly purposes so well, did not fall from the sky into their hands," Henigan said.

Allen Faraday, vice president of administration for Bushmaster, said the company did nothing wrong and sold the rifle legally to a firearms dealer. "We naturally don't feel it's legitimate," he said of the litigation. "Nowadays, lawyers are looking to file lawsuits wherever they can."

The owners of Bull's Eye Shooter Supply did not return phone calls for comment. Federal authorities have launched an investigation into how the rifle wound up with Muhammad and Malvo.

The Bushmaster rifle linked to the sniper shootings allegedly was sold or stolen from Bull's Eye Shooter Supply in Tacoma, Wash.