HARTFORD, Conn. -- The families of nine of the 26 people killed and a teacher wounded two years ago at the Sandy Hook Elementary School filed a lawsuit against the manufacturer, distributor and seller of the rifle used in the shooting.
The negligence and wrongful death lawsuit, filed in Bridgeport Superior Court and released on Monday, asserts that the Bushmaster AR-15 rifle should not have been sold publicly because it was designed for military use and is unsuited for hunting or home defense.
"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 defendants are Camfour, a firearm distributor, and Riverview Gun Sales, the now-closed East Windsor store where the gunman's mother purchased the Bushmaster rifle in 2010.
Messages seeking comment from the defendants were not immediately returned.
The so-called AR-15 rifle was first build by Armalite for military use, but the design was later acquired by Colt, which produced the M-16 automatic weapon for the U.S. military. In the early 1960s, Colt began marketing the semi-automatic AR-15 rifle as the civilian version of the fully automatic M-16. Many other companies have since begun manufacturing and selling AR-15-type rifles, including the Bushmaster X-15.
The rifles are extremely popular in shooting competitions due to the light weight of the gun and ammunition and the weapon's accuracy.
Bill Sherlach, whose wife, Mary, was killed in the shooting, said he believes in the Second Amendment but also that the gun industry needs to be held to "standard business practices" when it comes to assuming the risk for producing, making and selling a product.
"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.
The plaintiffs include Sherlach and the families of Vicki Soto, Dylan Hockley, Noah Pozner, Lauren Rousseau, Benjamin Wheeler, Jesse Lewis, Daniel Barden, Rachel D'Avino and teacher Natalie Hammond, who was injured in the shooting.
The lawsuit seeks unspecified monetary damages.
New York attorney Robert Fellows told CBS News correspondent Don Dahler the bar is high for a lawsuit.
"If you can prove that a manufacturer knew in some way that the gun would end up the hands of a proscribed purchaser, someone who shouldn't have the gun, you might be able to show liability. But it is going to be very difficult," he said.
Nicole Hockley, the mother of 6-year-old victim Dylan, and Mark Barden, the father of 7-year-old victim Daniel, appeared at a news conference Monday morning with U.S. Sens. Richard Blumenthal and Chris Murphy. They declined to comment on the lawsuit and instead pushed for new laws and programs to restrict access to weapons and improve mental health treatment.
"My little Daniel's death was preventable," Barden said. "Dylan Hockley's death was preventable."
The Newtown gunman, Adam Lanza, shot and killed his mother, Nancy Lanza, on the morning of Dec. 14, 2012, before driving to the school and gunning down 20 children and six educators with the semi-automatic rifle. He committed suicide as police arrived.
In 2005, Congress and President George W. Bush approved a federal law that shielded gun makers from lawsuits over criminal use of their products, with some exemptions.
In a lawsuit over the .223-caliber Bushmaster rifle used in the Washington, D.C.-area sniper shootings that killed 10 people in 2002, Bushmaster and a gun dealer agreed to pay $2.5 million to two survivors and six families in a 2004 settlement. It was the first time a gun manufacturer had agreed to pay damages to settle claims of negligent distribution of weapons, according to the Brady Center to Prevent Gun Violence.
In that settlement, Bushmaster paid $550,000 and the Washington state gun dealer, where the sniper's rifle came from, paid $2 million.
In 2002, a federal judge in California ruled that Bushmaster and other gun manufacturers were not responsible for a 1999 shooting spree that killed a postal worker and injured five people at a Jewish community center in Los Angeles. The judge said a lawsuit by the victims' families did not show a link between the manufacturers and the shooting rampage.
On Sunday, the community of Newtown quietly marked the second anniversary of the shooting. No public memorial events were held on a day town officials said instead would be for private reflection and remembrance.