The man responsible for the largest mass shooting in modern U.S. history could have used explosive chemicals to inflict even more damage, authorities say.
Las Vegas Police Department Sheriff Joseph Lombardo said Wednesday night that police had found 10 1-pound canisters and two 20-pound canisters of Tannerite in the car of Stephen Paddock. Paddock opened fire on a country music festival on Sunday, killing at least 59 people and wounding more than 500 others. Police said they also found ammonium nitrate in Paddock’s vehicle.
Tannerite is the brand name for an explosive primarily used for target practice. It can be bought at most gun shops or online.
“Our KICK-ASS invention is specifically designed to be safe,” the company that makes Tannerite says on its website. “We have spent many years perfecting our product.”
Hunters and long-distance shooters put Tannerite on targets, retired FBI agent Harold Copus told HuffPost. The substance helps them know when they’ve hit their mark because it causes a little explosion.
“A small amount is used for a target,” Copus said. “But 50 pounds, that’s significant. I would ask why did he have it? He certainly wasn’t going down there pasting targets on those people, so I suspect he had it because he was gonna create a bomb.”
Tannerite can cause severe burns and “major blast injury” to people who are close to it when it goes off, according to a 2016 study from the Environmental Protection Agency.
Authorities also found an unspecified amount of ammonium nitrate in Paddock’s car. The substance is primarily used in fertilizers, and the U.S. uses millions of tons of it each year. And although the risk of danger is low, the EPA said explosions involving ammonium nitrate can have “severe consequences.”
Those consequences were perhaps best seen in 2013, when 15 people were killed in an explosion at a fertilizer plant in Waco, Texas.
However, the chemical explosives remained untouched during Sunday night’s shooting.
“It remained in the car for some reason,” Lombardo said of the material.
Copus said gun stores typically sell Tannerite in 1-pound cans.
“I suspect he bought a lot of it [over] a longer term,” Copus said. Lombardo confirmed on Wednesday that Paddock had been stockpiling weapons for decades.
This article originally appeared on HuffPost.