The Los Angeles County Sheriff's Department tweeted that it had detained one person. School is clear. So far, no evidence of crime.
There were reports of one person injured.
The suspect was spotted on the campus of Highland High School in Palmdale early at 7:05 a.m., according to Nicole Nishida, a spokeswoman for the Sheriff's Department.
A woman told CBS Los Angeles that her son told her he was in class at the school and heard at least one gunshot.
Whatsapp Black Dot Message can Crash Your App and Phone
Then you can open the head named "New Messages 'and you can avoid opening the last message with the particular problematic emoji". A YouTube channel called EverythingApplePro has discovered this message and has also uploaded a video explaining what it does.
911 calls reported a man with a gun on campus around 7 a.m.
Deputies at the scene are clearing the school "methodically", and students will be transported home via school buses once the campus is deemed safe, Nishida said.
Sheriff's deputies in Palmdale also responded to reports of an active shooter at Manzanita Elementary School, which is located about eight miles from Highland High.
Deputy Charles Moore says there is no confirmation of an actual person with a gun or any shooting.
West, which was placed on lockdown along with all other schools in the Antelope Valley Union High School District.