A seventh-grade teacher was arrested on campus after he was seen smoking heroin, police say.

Kyle Patrick Mackenzie was arrested at 10 a.m. Tuesday, Oct. 7, at Jehue Middle School in Colton and booked for investigation of drug possession, jail records show. His bail is $25,000.

The 29-year-old teacher was immediately placed on paid administrative leave, as required by state law, said Rialto Unified School District spokeswoman Syeda Jafri.

“We cannot put him on unpaid administrative leave until charges are filed,” she said.

Named for former Rialto principal and district trustee William G. Jehue, the school is located at 1500 N. Eucalypus Ave. in Colton but is part of the Rialto school district.

A school worker sounded the alarm after seeing Mackenzie near the campus smoking something that clearly wasn’t a cigarette, said Cpl. Ray Mendez.

“The witness pretty much described that the person was smoking something out of aluminum foil,” Mendez said.

Heroin, methamphetamine and certain other narcotics often are smoked by placing the drug on aluminum foil that the smoker holds in one hand while using the other hand to heat the foil with a lighter, Mendez said.

A school administrator notified police, who questioned and arrested the teacher.

“Mackenzie was found to be in possession of heroin and admitted to smoking it,” he said.