Minnesota and New Jersey sued Glock on Thursday over the design of its iconic 9-millimeter semiautomatic pistol, claiming that the company had failed to make changes to prevent its easy conversion to a deadly, illegal machine gun.

Over the past few years, criminals, gang members and teenagers have fitted their Glock handguns with so-called switches: cheap, tiny and easily obtainable plastic blocks that can convert the semiautomatic pistol into an automatic weapon capable of firing dozens of bullets with a single pull of the trigger.

Law enforcement agencies around the country say the proliferation of switches, also known as auto sears, fueled the rise in shootings and murders during the coronavirus pandemic. They pose a growing risk to outgunned law enforcement officials and bystanders hit by the indiscriminate spray of bullets, a telltale sign of a pistol equipped with a switch.

The two suits — part of an aggressive push by Democratic attorneys general and gun control groups against manufacturers — claim that the company’s leaders have known for decades that two significant design characteristics of the weapon make it susceptible to conversion to a machine gun.

Not only have they rebuffed efforts of law enforcement officials to make the gun more difficult to alter, they have marketed it as customizable, according to the lawsuits, which were brought in conjunction with the national gun control group Giffords.

“Glock knows that its semiautomatic handguns are easily and frequently converted to illegal, fully automatic machine guns with Glock switches, and Glock knows that these fully automatic handguns present a significant threat to public safety,” the attorney general of Minnesota, Keith Ellison, wrote in a suit filed in federal court in Minneapolis.