The tornado hit in the Mesa public school district, leaving students and staff stranded at their school in the foothills of the Sierra Nevada mountains, but they’re all back on the job now, officials said on Monday.

Schools in the San Gabriel Unified School District in the El Cajon area of Los Angeles County were shuttered Monday because of the tornado, and more than 70 schools across California were affected.

More than 1,500 schools and 300 elementary schools were closed and reopened after the storm, officials told CBS Los Angeles.

School Superintendent Mike Pacheco said that many of the students were “very traumatized,” and that the district has a number of students from the affected areas who will be able to return to classes in the coming days.

He said that some students are in classrooms with other students, which may not be the best place for them to be.

Pacheco urged students to go back to school if they need to, but he urged parents to be vigilant about their childrens safety.

“I want to remind parents, please be aware of their kids and not be afraid to let your kids know if you have a concern,” he said.

Officials said at least one student has been admitted to a hospital after sustaining minor injuries in the tornado.

A tornado warning was issued for portions of the Los Angeles area for up to 24 hours, with heavy rain and wind gusts of 60 mph.

The National Weather Service said the threat has been extended to portions of Ventura County.

The weather service has been calling for rain in some areas as far south as Santa Barbara.

The Associated Press contributed to this report.