WOODLAND HILLS (CBSLA.com) — A 26-year-old man was arrested Thursday for allegedly posting a threat on social media that prompted an evacuation of Pierce College in Woodland Hills, authorities said.

The shutdown and evacuation of the campus in the 6200 block of Winnetka Avenue began about 8 a.m., according to the Los Angeles County Sheriff’s Department.

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School officials said the investigation began after a threat was made stating someone “might” come to campus with a gun.

Following the arrest, Pierce College officials said the campus was scheduled to reopen and classes would resume at 3:30 p.m., although there will be only “limited services on campus.”

Los Angeles County sheriff’s spokeswoman Nicole Nishida says the suspect, Sergio Castanon Jr. of Northridge – a former Pierce College student – was taken into custody on suspicion of making criminal threats.

Nishida says the school was evacuated and searched and nothing was found.

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Detectives conducted a search warrant for Castanon’s residence, where an assault rifle, handgun, several rounds of ammunition and illegal high capacity magazines were recovered, officials said.

(credit: Los Angeles County Sheriff's Department)

(credit: Los Angeles County Sheriff’s Department)

(credit: Los Angeles County Sheriff's Department)

(credit: Los Angeles County Sheriff’s Department)

The college, which has about 21,000 students, says classes will resume at 3:30 p.m. but the campus will only offer limited services.

Castanon is being held on $50,000 at the Malibu/Lost Hills Sheriff’s Station for criminal threats, possession of high capacity magazines and illegal ammunition.

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