A pro-Palestinian encampment on the campus of the University of Southern California was being cleared Sunday morning as campus police warned protesters to leave or be arrested.

The announcement came as the USC Department of Public Safety closed the campus "as a result of significant activity at the center of campus."

"If you are in the center of campus, please leave. People who don’t leave will be arrested. We will issue another alert when it is clear to return," the DPS said on X.

The campus police said officers from the Los Angeles Police Department are assisting in "clearing the center" of the University Park Campus.

Sunday's action came after USC President Carol Folt sent an email to the school's community, saying "steps would be taken to ensure a quiet and safe environment for students to complete their finals."

“[L]et me be absolutely clear: free speech and assembly do not include the right to obstruct equal access to campus, damage property, or foment harassment, violence, and threats,” Folt said. “Nor is anyone entitled to obstruct the normal functions of our university, including commencement."

-ABC News' Cory Peeler

Authorities arrested 25 protesters at the University of Virginia for trespassing on Saturday, according to the university's communications office.

The school said it was still awaiting confirmation on how many of those arrested were affiliated with UVA.

Approximately 50 people were arrested, including some students, at The Art Institute of Chicago on Saturday, according to a spokesperson from the museum.

"Today, a group of individuals, including some SAIC students, began a protest in the museum’s North Garden, and as it progressed, protesters surrounded and shoved a security officer and stole their keys to the museum, blocked emergency exits, and barricaded gates," the statement read.

Protesters were offered an alternative location to continue the protest on campus, but they did not accept that offer, according to the spokesperson.

"During multiple rounds of negotiations, SAIC student protesters were promised amnesty from academic sanction and trespassing charges if they agreed to relocate. The School also agreed to meet with a student group to discuss their demands. After approximately five hours, an agreement could not be reached."

Chicago Police Department assisted with ending the protests and arresting individuals, the museum spokesperson said.

The president of the University of Virginia, Jim Ryan, released a statement Saturday on the removal of protesters from the encampment on campus.

Ryan said that up until Friday, the demonstrations on campus had remained peaceful and "complied with requests to adhere to University policies including a long-standing prohibition on erecting tents absent a permit."

However, Ryan said protesters were given a "final warning" on Saturday morning that "was ignored" and the university’s police department officers "were met with physical confrontation and attempted assault."

Virginia State Police were called to clear the encampment after it was deemed an "unlawful" assembly, according to the president.

"I recognize and respect that some will disagree with our decisions,” Ryan said in the statement. “This entire episode was upsetting, frightening and sad."

In a letter authorizing the NYPD to enter the Columbia University campus and break up the protest, the school detailed the backstory on its recent talks with those in the encampments and the takeover Tuesday night of Hamilton Hall.

According to the letter, from Columbia President Minouche Shafik, an individual "hid in the building" at Hamilton Hall until it was closed and let others in. The group's purpose was "occupying the building," the letter read.

Two security guards were inside the building at the time, and the university said in the letter to the NYPD they were able to "secure their release."

"We believe that while the group who broke into the building includes students, it is led by individuals who are not affiliated with the University," the letter read. "The individuals who have occupied Hamilton Hall have vandalized University property and are trespassing."
Addressing the encampment on the school's Morningside campus, the university told police discussions had been carried out with group representatives, but on Sunday, they "reached an impasse."

At that time, the university says it told the group they did not have permission to "occupy spaces on campus" and were "in violation" of school rules and policies.
On Monday morning, the protesters were told they would be suspended if they didn't disperse by Monday at 2 p.m. ET.

The university said in its Tuesday night NYPD letter that those in the encampment were "suspended" and "not authorized to be on University property and are trespassing."

The university said it believed the actions of those in the protest were escalating. "These activities have become a magnet for protesters outside our gates which creates significant risk to our campus and disrupts the ability of the University to continue normal operations," the letter read.

Columbia's president concluded the letter by asking the NYPD to "help to clear all individuals from Hamilton Hall and all campus encampments."

She further asked police to have a campus presence through May 17 -- graduation is May 15 -- "to maintain order and ensure encampments are not reestablished."

Police moved onto the Columbia University campus a little before 9 p.m. ET and began making arrests.

The NYPD also used a vehicle with an extendable roof ramp to help officers breach Hamilton Hall from an upper floor. From there, the police cleared the building.

The campus encampment and hall were cleared before 11:30 p.m.

-ABC News' Jolie Lash, Aaron Katersky and Joshua Hoyos