NEW YORK: Families of nine victims of the Sandy Hook school shooting have reached a $73 million settlement with US gunmaker Remington, in a landmark deal for a country traumatized by campus massacres. Lawyers for the plaintiffs said the settlement marks the first time a gun maker has been held liable for a mass shooting in the United States.

Twenty-six children and teachers were shot dead in 2012 at the elementary school in Newtown, Connecticut by Adam Lanza, a 20-year-old with known developmental disabilities.

The killings — the second-deadliest school massacre in US history — stunned Americans, with many thinking they would mark a watershed moment that would lead lawmakers to tighten gun control.

A “settlement agreement has been executed between the parties,” a notice from lawyers for the families said Tuesday. Calling the move “historic,” US President Joe Biden said it begins “the necessary work of holding gun manufacturers accountable.”

Manufacturers and dealers must either change their business models or “bear the financial cost of their complicity,” he said in a statement.

Lanza’s mother, a gun enthusiast, had bought him an AR-15-style Bushmaster XM15-E2S semi-automatic rifle more than two years before the shooting.

Lanza murdered his mother before attacking the school, and killed himself afterward.

The lawsuit alleged that Remington and the other two defendants are culpable because they knowingly marketed a military grade weapon that is “grossly unsuited” for civilian use yet had become the gun most used in mass shootings.

An AR-15 was also used to kill 58 people at a mass shooting in Las Vegas in 2017, and 17 at a school in Parkland, Florida in 2018.

Remington, the oldest gunmaker in the United States and which has since filed for bankruptcy, had denied the allegations.

The plaintiffs alleged that the gun was marketed immorally and unscrupulously and sold on its war-fighting capabilities to civilians.

Marketing, they charged, popularized the AR-15 in combat and mass shooting-type situations through the type of violent video games that Lanza was known to play.

They specifically cited Remington’s marketing of high-capacity magazines, which have only combat utility, for use with the gun.

The gun “was used not by a highly trained soldier but by a deeply troubled kid, not on a battlefield abroad but in an elementary school at home, and not to preserve freedom, but to eviscerate them,” Joshua Koskoff, a lawyer for the Sandy Hook families, told a press conference Tuesday.