BRIDGEPORT — The estates of nine of 26 people who were killed and one teacher who was injured in the December 14, 2012, shooting at Sandy Hook Elementary School are the plaintiffs in a negligence and wrongful death lawsuit lodged against the manufacturer, the distributor, and the seller of the semiautomatic Bushmaster AR-15 rifle, which a 20-year-old gunman used in the murders.

Koskoff, Koskoff & Bieder, PC, of Bridgeport filed the lawsuit December 15 in Bridgeport Superior Court. The court return date for the defendants is February 3.

Among those named as defendants are Bushmaster Firearms International, LLC, of North Carolina, which is the manufacturer; Camfour, Inc, of Massachusetts, which is the distributor; and Riverview Sales, Inc, of East Windsor, which is the gun shop where the weapon was purchased; and gun seller David Laguercia.

Named as plaintiffs in the lawsuit are the estates of students Dylan Hockley, Noah Pozner, Benjamin Wheeler, Jesse McCord Lewis, and Daniel Barden; the estates of teacher Victoria Soto, school psychologist Mary Joy Sherlach, teacher Lauren Rousseau, and school therapist Rachel D’Avino, and surviving injured teacher Natalie Hammond. The students were first graders.

The 40-page lawsuit, which seeks money damages and injunctive relief, states that on December 14, 2012, in less than five minutes, 20 students and six adults were killed, with two other people wounded at the hands of the gunman wielding a powerful military-style firearm.

The shooter discharged 154 rounds from the AR-15 rifle, according to police.

So many people died during such a brief period because the weapon used was designed as a military weapon for battlefield use and intended for maximum damage, according to the lawsuit.

“Time and again, mentally unstable individuals and criminals have acquired an AR-15 with ease, and they have unleashed the rifle’s lethal power into our streets, our malls, our places of worship, and our schools,” the plaintiffs note, adding, “[The] defendants know that, as a result of selling AR-15’s to the civilian market, individuals unfit to operate these weapons gain access to them.

“In order to continue profiting from the sale of AR-15’s, [the] defendants chose to disregard the unreasonable risks the rifle posed outside of specialized, highly regulated institutions like the armed forces and law enforcement,” according to the lawsuit.

Through the legal action, the plaintiffs are seeking accountability for the consequences of such gun sales, the plaintiffs state.

On December 16, the Newtown-based National Shooting Sports Foundation (NSSF) issued a statement in response to the lawsuit. NSSF is a national trade association for the firearms industry.

“The US Congress, with overwhelming bipartisan support, passed the Protection of Lawful Commerce in Firearms Act in 2005 in order to prevent lawsuits that seek to blame manufacturers for the criminal misuse of products that were lawfully sold,” the trade group noted in its statement.

“Like all Americans, we have great sympathy for the families represented in this suit. This tragedy was caused by the criminal actions of a mentally unstable individual. The suit lacks factual and legal merit,” according to NSSF.

Generally, the plaintiffs allege that the AR-15 rifle should not have been publicly sold for civilian use because it is a military-type weapon designed for battlefield use.

The Bushmaster XM15-E2S was the model of the AR-15 that was used by Adam Lanza in the shooting. Nancy Lanza, 52, his mother, who owned the weapon, had purchased it at Riverview Sales in March 2010.

On the morning of December 14, 2012, Adam Lanza shot and killed his mother with another rifle at their Yogananda Street home before driving to Sandy Hook School where he shot the students and educators with the AR-15 before killing himself with yet another firearm.

Adam Lanza brought ten 30-round magazines with him to the school after having taken the Bushmaster and the ammunition from an unlocked gun closet in his house, according to the lawsuit.

Through the lawsuit, the plaintiffs are seeking unspecified money damages exceeding $15,000, punitive damages, attorneys’ fees, court costs, and injunctive relief.