LOS ANGELES — Police removed barricades and began dismantling a pro-Palestinian demonstrators’ fortified encampment early Thursday morning at the University of California, Los Angeles, after hundreds of protesters defied orders to leave. Some people were detained, their hands bound with zip ties.

The action came after officers spent hours threatening arrests over loudspeakers if people did not disperse. A crowd of more than 1,000 had gathered on campus, both inside a barricaded tent encampment and outside it, in support. Protesters and police shoved and scuffled as officers encountered resistance.

With police helicopters hovering, the air was pierced by the sound of flash-bangs, which produce a bright light and a loud noise to disorient and stun people. Protesters chanted, “Where were you last night?” at the officers, in reference to Tuesday night, when counterprotesters attacked the encampment and the UCLA administration and campus police took hours to respond.

California Highway Patrol officers poured into the campus by the hundreds early Thursday. Wearing face shields and protective vests, they stood with their batons protruding out to separate them from demonstrators, who wore helmets and gas masks and chanted, “You want peace. We want justice.”

Numerous protesters were arrested, their hands bound with zip ties. Video footage from the morning showed some sitting with their hands behind their backs on the sidewalk as police walked around and buses sat nearby.

In the Mideast, Iranian state television carried live images of the police action, as did Qatar’s pan-Arab Al Jazeera satellite network. Live images of Los Angeles also played across Israeli television networks, as well.

UCLA Chancellor Says Instigators Came on Campus

UCLA Chancellor Gene Block said in a statement Wednesday that “a group of instigators” came on campus to “forcefully attack” the pro-Palestinian encampment, prompting the school to ask for assistance from outside law enforcement agencies.

“However one feels about the encampment, this attack on our students, faculty and community members was utterly unacceptable,” Block said. “It has shaken our campus to its core.”

Block promised the university will conduct a thorough investigation.

Muslim Groups Blast UCLA for Failing to Protect Palestinian Supporters

Muslim organizations and students blasted UCLA officials and police in a Wednesday news conference, saying they failed to intervene as students in pro-Palestinian encampment on the Los Angeles campus were verbally harassed, pepper sprayed and beaten during a brawl with counter-protesters earlier in the day.

“The community needs to feel the police are protecting them, not enabling others to harm them,” said Rebecca Husaini, chief of staff for the Muslim Public Affairs Council.

Speakers disputed the university’s account that 15 people were injured and one hospitalized, saying the number of people taken to the hospital was higher. One student described needing to go to the hospital after being hit in the head by an object wielded by counter-protesters.

Several students who spoke said they had to rely on each other, not the police, for support as they were attacked, and that many in the pro-Palestinian encampment remained peaceful and did not engage with counter-protesters.