INDIANAPOLIS (AP) — School resource officers at Indiana’s largest high school are reporting a surge in students being sent to hospital emergency rooms after they used marijuana’s psychoactive ingredient in electronic cigarettes to get high.

The Indianapolis Star reports that Carmel High School resource officer Shane VanNatter says he’s seen students who’ve vaped THC walking school hallways “so stoned that they don’t know where they are.”

VanNatter says 17 students at the suburban Indianapolis school with an enrollment of about 5,000 students have been caught this school year for using, possessing or dealing THC vaping products.

Experts say those products’ potency can give students a much more powerful high than expected.

VanNatter seized one vaping cartridge that contained THC levels exceeding 80%.

THC levels in marijuana plants typically range from 15% to 24%.