The sign for the new Sandy Hook Elementary School at the end of the drive leading to the school is pictured in Newtown, Connecticut, U.S. July 29, 2016. The officials unveiled the newly constructed school, built to replace the building torn down after a g
The sign for the new Sandy Hook Elementary School at the end of the drive leading to the school is pictured in Newtown, Connecticut, U.S. July 29, 2016. The officials unveiled the newly constructed school, built to replace the building torn down after a gunman shot dead 20 young children and six educators in a 2012 massacre. Reuters / Michelle McLoughlin

Remington Arms will pay $73 million to the families of five adults and four children killed in the Sandy Hook Elementary School massacre, the families said on Tuesday, the first time a gunmaker has been held liable for a mass shooting in the United States.

Twenty students and six adults were killed on Dec. 14, 2012 in Newtown, Connecticut by gunman Adam Lanza, who used a Remington Bushmaster AR-15 rifle to shoot his way into the Sandy Hook Elementary School after killing his mother at home.

Remington Arms will pay $73 million to the families and release all the discovery and disposition material to the public. The settlement will be paid through insurance policies.

The nine families sued in 2014 and spent years in the courts trying to hold Remington liable, despite a U.S. law that protects gunmakers and dealers from most civil litigation.

"They had the energy, drive and motivation to do one thing. That was to do whatever they could so that other families ... would not have to go through the pain and loss that they have," said Josh Koskoff, an attorney for the families.

The Sandy Hook families found a way around that legal protection for gunmakers by claiming that Remington's marketing of firearms contributed to the massacre.

Other gun control advocates have since been encouraged to follow that strategy, including New Jersey's attorney general who is investigating Smith & Wesson's marketing.

Mexico filed a U.S. lawsuit last year seeking $10 billion from several gunmakers, accusing them of marketing their weapons to the country's underworld.

New York last year enacted a law that allows firearm sellers, manufacturers and distributors to be sued for creating a "public nuisance" that endangers the public's safety and health. Gun manufacturers have challenged the law in court.

Gun groups have also been using the courts and state legislatures to expand gun rights and have scored victories at the Supreme Court in 2008 and 2010 that established an individual's right to keep a gun at home for self-defense.