Dozens of protesters gathered Monday in Oakland outside Oaksterdam University, chanting "DEA, Go Away" as U.S. marshals stood at the medical marijuana school's doors behind yellow police tape.

Supporters of Richard Lee, who founded the state's first cannabis-industry training school, said he was detained temporarily by unknown federal agents at his nearby apartment but had been released.

A DEA spokeswoman confirmed Lee was detained for questioning and released and that his home was raided.

PHOTOS: Feds raid medical cannabis school in Oakland

"I'm outraged," said Jane Klein, 63, of Oakland, whose Marijuana Growers Handbook is used by the trade school.

Her husband, longtime marijuana advocate Ed Rosenthal, 66, is on the faculty.