A Riverside, CA, elementary school was evacuated Tuesday when an upset parent barricaded himself in a classroom with a teacher, reports KNBC.

Castle View Elementary School was placed on lockdown in the noon hour after the assault.

The parent entered the campus and punched a teacher. Riverside Fire Department officials said the victim was taken to Riverside Community Hospital for treatment. Witnesses at the scene said the injured person appeared to have a bloody or broken nose.

The assailant, whose identity had not been confirmed, barricaded himself in a classroom with first-grade teacher Linda Montgomery, according to her daughter.

"He’s not responding to our commands to come out so far," Riverside Police Officer Ryan Railsback told the Los Angeles Times. Witnesses did not report seeing any weapons on the man, police said.

Smoke was briefly seen coming out of the room, but Railsback said he didn’t have any information about it. It did not appear to be toxic, he said.

The campus was initially placed on lockdown, then evacuated, KNBC reports. Students and staff were moved to nearby Castle View Park for their safety, according to police.

There were no reports of injuries to students. Riverside Unified School District officials said all students had been accounted for and were being released to their parents at the park.