Colorado authorities have arrested a suspect who they say threatened a mass shooting at UCLA, according to a report.

The suspect was apprehended Tuesday, KABC-TV of Los Angeles reported. The man's identity was not immediately revealed, but the Los Angeles Times identified him as Matthew Harris, a former UCLA lecturer and postdoctoral fellow.

Authorities say the suspect made threats to UCLA's philosophy department and wrote an 800-page manifesto containing racist, misogynistic and anti-Semitic remarks.  

UCLA DEPARTMENT CANCELS IN-PERSON CLASSES AFTER APPARENT MASS SHOOTING THREAT: REPORT 

"The material includes a video entitled ‘UCLA Philosophy Mass Shooting’ and an 800-page manifesto with specific threats towards some members of our department," a UCLA email sent to students this week said, according to the L.A. Times

UCLA canceled Tuesday's in-person classes in response, holding virtual lectures instead. 

Harris had posted about 300 videos to a YouTube account, with most of them published Monday, according to Newsweek. His account on Tuesday featured a message from YouTube stating the page was "terminated due to multiple or severe violations of YouTube's policy prohibiting hate speech."

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Titles of videos he allegedly posted to YouTube include: "MURDER," "my racial angel I'm so glad you exist" and "im a p*dophile, ladies im a p*dophile," Newsweek reported