How the UCLA Protest Standoff Unfolded

As protesters chanted and sprayed fire extinguishers at them, police officers moved in on the pro-Palestinian encampment at the University of California, Los Angeles, in the early hours of Thursday, tearing down its barricades, arresting dozens of people and clearing out the tents that had dominated the center of campus for days.

The chaotic scenes were part of a tense, hourslong back-and-forth between protesters and police that had been building after violent clashes a day earlier — involving counterprotesters who attacked the encampment — prompted administrators to call in law enforcement.

On Wednesday night, the authorities issued a warning to pro-Palestinian demonstrators: Leave the encampment outside Royce Hall or face arrest.

As the night wore on, officers in riot gear tried to approach the encampment through one of its entrances but were turned back several times.

Demonstrators appeared to try several tactics to fend them off. At one point, they blocked an entrance with wooden pallets and homemade shields. They surrounded police officers, chanting “Free, free Palestine!” and “Peaceful protest!” At another point, they opened umbrellas and began flashing lights and taking photos of the police officers.

Then, at around 3 a.m. Thursday, officers breached one of the barricades at the encampment and began to pull apart plywood and other materials that demonstrators had used to build a wall. Some demonstrators sprayed fire extinguishers in response, briefly forcing some officers to fall back.

But an hour into the raid, the encampment’s main barricade had been dismantled. A line of students linking arms took its place.

Officers gave another dispersal warning to protesters. They corralled those who refused to leave and began arresting them, zip-tying their wrists and leading them away from the encampment.

Police pulled up tents — one removed a Palestinian flag and tossed it aside — and at several points fired devices at demonstrators. It was not clear what the officers were using, but Erik Larsen, an officer for the California Highway Patrol, said in a telephone interview that its officers were equipped with a variety of “nonlethal” tools, including flash-bang devices.

By dawn, the camp had been cleared of all but a final group of demonstrators, some of whom chanted, “We’ll be back, and we’ll be stronger — you cannot ignore us any longer.” Some were detained and marched away with their hands zip-tied behind their back.

The C.H.P. — which, in addition to patrolling state highways is responsible for the safekeeping of state property, including public universities like U.C.L.A. — said that 132 demonstrators had been arrested and would be handed over to the university’s police department. At least 250 C.H.P. officers were involved in clearing the encampment, Mr. Larsen said.

Other law enforcement agencies, including the Los Angeles Police Department, the Los Angeles County Sheriff’s Department and the U.C.L.A. university police, were also on the scene, he said.