Police have arrested an 18-year-old they say threatened in an online post to “start a massacre” at Montebello High School, where he’d been expelled for making similar threats.

Late Friday night, officers went to the 500 block of South Sixth Street, where a woman told them her son had seen an alarming Instagram post, the Montebello Police Department said.

In the post, a man said that “he was going to take a gun and start a massacre at Montebello High School on Monday,” according to a written statement from the police department.

Officers were able to locate the man, who denied posting the threat, authorities said.


“When the officers asked the male subject to go into his Instagram post, he told the officers that he was unable to access it,” officials said.

Police arrested Montebello resident Devin Harper on suspicion of making criminal threats. He remained in custody Monday afternoon in lieu of $50,000 bail, custody records show. He is scheduled to appear in court Tuesday.

Authorities said Harper attended Montebello High until he was expelled about two years ago.

There are no additional credible threats to the school, according to the Los Angeles County Sheriff’s Department’s East L.A. Station.


As a precaution, the department will coordinate with other agencies “to boost patrol in the areas the station serves,” officials wrote on Twitter.

Recently there was an arrest related to threats @ #Montebello HS. @EastLALASD wants concerned parents 2 know there are no credible additional threats. As a precaution, #LASD is coordinating w/ surrounding agencies to boost patrol in the areas the station serves. — LASD East LA Station (@EastLALASD) March 2, 2020

In a written statement, Montebello Unified School District officials said they take such threats “very seriously.”

“The safety of our schools, students and personnel continues to be our top priority,” they said Monday. “Out of an abundance of caution, we have officers from school police on and around our campus. All classes are resuming on a normal schedule. Any matters relating to the safety on our campuses will be addressed swiftly and appropriately.”