Seattle ? 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.

Muhammad and Malvo are accused of killing 13 people and wounding five others. Investigators are trying to determine how 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, was killed Oct. 22 in Aspen Hill, Md.