Relatives of two Washington, D.C.-area sniper victims on Thursday sued a gun manufacturer and store linked to the Bushmaster XM15 assault rifle used in the deadly attacks.

The family members of James "Sonny" Buchanan and Conrad Johnson claim the gunmaker and store showed "gross negligence" that caused injuries and death, according to the complaint. The relatives are represented by the Brady Center to Prevent Gun Violence.

The case, filed in Pierce County Superior Court in Tacoma, seeks unspecified damages. It names Bull's Eye Shooter Supply of Tacoma, which either sold the rifle or lost it in a theft; store owners Brian Borgelt and Charles Carr; Bushmaster Firearms Inc. of Windham, Maine; and sniper defendants John Allen Muhammad and Lee Malvo.

"If Bull's Eye and Bushmaster and the other gun industry defendants had acted responsibly in the sale of their guns, Muhammad and Malvo would not have been able to obtain the assault rifle they needed to carry out their shootings," the lawsuit claims.

The lawsuit alleges that at least 238 guns, including the assault rifle, disappeared from the gun shop in the last three years. Despite audits by the Bureau of Alcohol, Tobacco and Firearms showing Bull's Eye had dozens of missing guns, Bushmaster continued to use the shop as a dealer, the lawsuit alleges.

The Bull's Eye owners didn't return phone calls for comment. Allen Faraday, vice president of administration for Bushmaster, said the company did nothing wrong and that it sold the rifle legally to a firearms dealer.

"We naturally don't feel it's legitimate," Faraday said of the lawsuit. "Nowadays, lawyers are looking to file lawsuits wherever they can."

The plaintiffs' attorney, Paul Luvera, said in a statement that the rifle was used in the sniper attacks less than three months after Bull's Eye received it in its store.

"Such a swift 'time to crime' is highly indicative of grossly negligent sales and distribution practices on the part of Bull's Eye and the gun industry defendant," he said.

Muhammad and Malvo are accused of killing 13 people and wounding five others in Alabama, Georgia, Louisiana, Maryland, Virginia and Washington, D.C. They are being tried first in Virginia in separate cases, and both could face the death penalty.

Investigators are trying to determine how exactly Muhammad and Malvo wound up with the rifle.

Buchanan, 39, was killed Oct. 3 while mowing grass at a car dealership near White Flint Mall; Johnson, 35, a bus driver, was killed on Oct. 22 in Aspen Hill, Md.

Dennis Henigan, legal director of the Brady Center, said at least three more families of sniper victims plan to join the lawsuit. The organization has filed more than two dozen similar suits on behalf of municipalities and individuals.

Buchanan's sister, Vickie Snyder of Rockville, Md., said she hopes that, ultimately, there will be more control over who obtains firearms.

"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," she said.