The families of nine victims of the Dec. 14, 2012, massacre at Sandy Hook Elementary School in Newtown, Connecticut, have joined forces with a teacher who was shot multiple times during the slaughter to sue Bushmaster, the maker of the firearm that gunman Adam Lanza used to kill 26 people, 20 of whom were children. The wrongful death lawsuit, which sparked the rage of gun rights advocates, contends that Bushmaster Firearms International's AR-15 rifle is a military-grade weapon that should not be available for public use, as they do not see it as a practical choice for activities such as hunting or self-defense.

The suit calls the AR-15 the "weapon of choice" for those who carry out mass shootings. "The AR-15 was specifically engineered for the United States military to meet the needs of changing warfare," the plaintiffs' attorney, Josh Koskoff, said in a statement, the Associated Press reported. "In fact, one of the Army's specifications for the AR-15 was that it has the capability to penetrate a steel helmet."

The suit, announced Monday, a day after the two-year anniversary of the Sandy Hook tragedy, which is one of the worst mass shootings in American history, immediately drew the ire of gun rights advocates on social media sites such as Twitter, who argued that the gunmaker should not be held responsible for Lanza's actions. Their reactions ranged widely from disagreement with the suit's premise and impassioned defenses of the Second Amendment to callous dismissals of the families' ongoing grief over having their loved ones killed in cold blood.

The lawsuit filed in Bridgeport Superior Court seeks unspecified damages from Bushmaster, and also names the gun distribution outfit Camfour and East Windsor, Connectiut, firearm retailer Riverview Gun Sales -- the shop that legally sold the AR-15 to Lanza's mother in 2010 -- as defendants.

In the two years since the Newtown shooting spree, at least 95 school shooting incidents have taken place in 33 states from California to Maine, according to a study released last week by Everytown for Gun Safety and Moms Demand Action for Gun Sense in America.

Bill Sherlach, a plaintiff in the lawsuit who lost his wife Mary in the Newtown massacre, said he is a supporter of gun rights, but that "standard business practices" need to followed in the firearm industry, the AP reported. "These companies assume no responsibility for marketing and selling a product to the general population who are not trained to use it nor even understand the power of it," he said.

But George Kollitides, chief executive of Remington Outdoor Company, which owns Bushmaster, told the Washington Times in June 2013 that Lanza is solely responsible for the massacre, the Wall Street Journal reported. “It’s very easy to blame an inanimate object,” Mr. Kollitides said. “Any kind of instrument in the wrong hands can be put to evil use. This comes down to intent - criminal behavior, accountability and responsibility.”