The family of the ex-Marine who invented the AR-15 rifle, a weapon style that has been used in a number of mass shootings, including last weekend’s massacre in Orlando, Florida, say the inventor never intended it for civilian use.

“Our father, Eugene Stoner, designed the AR-15 and subsequent M-16 as a military weapon to give our soldiers an advantage over the AK-47,” the Stoner family told NBC News Wednesday in emails and phone calls. “He died long before any mass shootings occurred. But, we do think he would have been horrified and sickened as anyone, if not more by these events.”

The gunman who went on a rampage at Pulse, an LGBT nightclub in Orlando, used a spinoff of an AR-15, a Sig Sauer MCX, and a Glock pistol to kill 49 people and wound 53 more. AR-15s were also used in the mass shootings at a Newtown, Connecticut elementary school, a movie theater in Aurora, Colorado and an office holiday party in San Bernardino, California.

Shooting enthusiasts argue that the weapon, which can fire off multiple rounds in seconds, is useful for hunting. Gun control advocates say powerful military weapons have no business being in the hands of civilians.

Stoner’s family members, who chose to remain individually anonymous, told NBC that the inventor never owned the weapon as an “avid sportsman, hunter and skeet shooter.”

Stoner first invented the AR-15 in the late 1950s in his garage and later helped sell it to the military as chief designer for ArmaLite, according to NBC. After his death in 1997, a semi-automatic version of the weapon became a bestseller among civilians, prompting the National Rifle Association to label it “America’s rifle.”

Sales of AR-15s have spiked in the days since the Orlando massacre, according to gun shop owners across the country—a common occurrence after mass shootings.