WESTWOOD, LOS ANGELES (KABC) — A pro-Palestinian encampment on the UCLA campus was largely cleared by law enforcement officers Thursday morning, resulting in the arrests of protesters who remained there for hours after they were ordered to leave.

A dispersal order was issued Wednesday evening and by 3:30 a.m. Thursday, CHP officers in riot gear began advancing on the encampment. They then began dismantling and tearing away pieces of plywood, metal barriers and other items that protesters used to fortify it.

Officials could not provide an exact number of arrests, but CHP Officer Alec Pereyda said it was in the hundreds. They were detained with zip ties.

The law enforcement action came after officers spent hours threatening arrests over loud speakers if people did not disperse. Hundreds of people had gathered on campus, both inside a barricaded tent encampment and outside of it in support.

As police helicopters hovered overhead, the sound of flash-bangs, which produce a bright light and a loud noise to disorient and stun people, could be heard as police moved in.

CHP officers wearing face shields and protective vests 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.”

Police methodically ripped apart the encampment’s barricade of plywood, pallets, metal fences and trash dumpsters and made an opening toward dozens of tents of demonstrators. Police also began to pull down canopies and tents. Demonstrators held umbrellas like shields as they faced off with dozens of officers.

As officers worked their way into the encampment, taking protesters into custody as they went, a core group of protesters formed a line and linked arms while face-to-face with law enforcement officers.

As the morning progressed, the number of those detained swelled into the hundreds. Most of them went peacefully. One young man was briefly pinned to the ground by officers before he was escorted away.

The encampment was eventually cleared of protesters, but their tents, equipment and other items were left behind.

As the morning progressed, the number of those detained swelled into the hundreds. Most of them went peacefully. One young man was briefly pinned to the ground by officers before he was escorted away.

It’s unclear how many of those detained were students.

Earlier in the morning, LAPD officers broke through an area of the encampment and came face to face with protesters. The protesters – outnumbering the officers – suddenly converged on police, forcing them to retreat. Up to that point, police had positioned themselves on the outskirts of the encampment.

For most of the night and into the early morning, the situation seemed tense but there were no drastic moments of violence between the two sides.

The dispersal order was issued after 6 p.m. Wednesday, and the Los Angeles Police Department declared a tactical alert as officers in riot gear positioned themselves on campus to remove protesters who all day had been signaling their intentions to dig in to their positions.

The law enforcement presence stood in contrast to the scene that unfolded Tuesday night, when counter-demonstrators attacked the pro-Palestinian encampment.

UCLA administration and campus police waited hours to stop the counterprotesters’ attack. The delay drew condemnation from Muslim students and California Gov. Gavin Newsom.

Demonstrators rebuilt the makeshift barriers around their tents on Wednesday while state and campus police watched.

At least 15 people were injured during hours of clashes Tuesday night. There was no police presence on campus for at least three hours as protesters and counter-protesters fought, in some cases using metal barricades and plywood as weapons, as well as deploying bear spray and tear gas.

The Associated Press contributed to this report.