The campus police chief for the University of California, Los Angeles, has been removed from his post in the aftermath of a violent, hourslong attack on a pro-Palestinian encampment at the school, during which security officers did not intervene.

The chief, John Thomas, has been reassigned temporarily while the university examines its security processes, according to U.C.L.A. officials.

Mr. Thomas had been under intense criticism over the university’s delayed response to the melee that broke…