Families of nine of the victims killed at the Sandy Hook Elementary School and an injured teacher filed a lawsuit in Connecticut state court on Monday against the manufacturer of the rifle used in the 2012 massacre, plus the distributor and the gun store where it was sold.

The negligence and wrongful death lawsuit, filed on the second anniversary of the mass shooting, asserts that the Bushmaster AR-15 rifle should not have been made publicly available because it's a military weapon unsuited for civilian use.

"In order to continue profiting from the sale of AR-15s, defendants chose to disregard the unreasonable risks the rifle posed outside of specialized, highly regulated institutions like the armed forces and law enforcement," the plaintiffs wrote in the complaint.

In addition to Bushmaster, the families have named Camfour, a firearm distributor, and Riverview Gun Sales, the store where the Bushmaster rifle was purchased by the shooter's mother, Nancy Lanza in 2010.

The civil action, which seeks unspecified damages, was filed in Superior Court in Bridgeport, Connecticut, and asserts the following:

"In less than five minutes, 20 first grade children and 6 adults were killed. Two others were wounded. ... The number of lives lost in those 264 seconds was made possible by the shooter's weapon of choice: a Bushmaster AR-15 rifle. ... The AR-15 was designed as a military weapon, and it has always excelled on the battlefield. Born out of the exigencies of modern combat, the AR-15 was engineered to deliver maximum carnage with extreme efficiency."

The families are represented by the law firm Koskoff, Koskoff & Beider of Bridgeport, Connecticut.

"The weapon was not designed for home defense or hunting. This weapon was designed to efficiently kill other human beings in combat," Josh Koskoff told the Hartford Courant.

The defendants named in the lawsuit have not responded to press inquiries, according to The Associated Press.

Critics argue the bar is high for a lawsuit because plaintiffs will have to be prove the manufacturers knew the gun would end up in the hands of the purchaser. Gun manufacturers are also shielded by Protection of Lawful Commerce in Arms Act, which offers broad immunity from lawsuits filed by victims of gun violence.