Portland police say that at least 30 people have been arrested over their involvement in ongoing protests at Portland State University.

"Additional arrests have been made at PSU’s library after trespassers illegally entered the building again despite efforts to secure it," police said in their statement. "Preliminary count is 30 arrests over the course of the day. Officers will continue to monitor for criminal activity and will make arrests when lawful and appropriate."

Authorities say that officers encountered acts of vandalism, and one suspect deployed a fire extinguisher at an officer during an altercation.

"Seven officers suffered injuries, the most serious was a knee injury that required ambulance transport to the hospital. Other injuries are still being assessed or were minor," Portland police said.

The identities of those arrested will be released once a full list has been completed.

USC has sent an email to the arrested protesters on Thursday evening warning that any student protesters who have been arrested for their "alleged conduct" of criminal trespassing on April 24 will be “referred to the University’s disciplinary process.”

"Please be aware that any further violation of university policies - including but not limited to the university's policies against camping, amplified sound, defying DPS directives, vandalism, harassments, bullying, and theft of property - will result in further discipline up to expulsion as well as an immediate ban from campus," the email obtained by ABC News said.

The Portland Police Bureau announced seven additional arrests were made Thursday evening amid ongoing protests at Portland State University.

The seven arrests came a couple of hours after PPB announced 22 people had been arrested on Thursday, bringing the total to 29 people arrested on Thursday.

PPB said the seven arrests were from "trespassers" breaking "back into the library" by pulling the fence down.

"Arrests have also been made for people refusing to leave the park block at the library," the bureau said in an update on X late Thursday evening.

The Portland Police Bureau said 22 arrests have been made amid the ongoing protests at Portland State University.

"PPB has arrested a total of 22 people during the events on the PSU campus," the bureau said in an update on X Thursday.

Earlier in the day, Oregon Gov. Tina Kotek released a statement condemning vandalism reported at the PSU Library.

“I fully condemn the criminal actions taken Thursday morning that resulted in the burning of 15 Portland Police Bureau cars, endangering first responders and the surrounding community," Kotek said, adding, "This includes the acts of vandalism seen this week at the Portland State University library and against nearby businesses."

University of California President Michael V. Drake addressed the ongoing protests at UCLA that "turned violent" overnight, announcing in a statement on Wednesday an "independent external review" has been ordered.

The university summoned mutual aid from LAPD officers to "restore control" to the protest, according to Drake, who noted, there were 15 injuries, including one hospitalization, that stemmed from the protest.

"My office has requested a detailed accounting from the campus about what transpired in the early morning hours today," Drake said.

"But some confusion remains, therefore we are also ordering an independent external review of both UCLA’s planning and actions, and the effectiveness of the mutual aid response," Drake said.

UCLA's own chancellor, Gene D. Block, also promised an investigation.

"We are still gathering information about the attack on the encampment last night, and I can assure you that we will conduct a thorough investigation that may lead to arrests, expulsions and dismissals," Block told the campus community in a note Wednesday afternoon.

Block, in his note, said it was "a group of instigators" who came to Royce Quad to "forcefully attack the encampment that has been established there to advocate for Palestinian rights."

He called the overnight violence "utterly unacceptable."

"However one feels about the encampment, this attack on our students, faculty and community members was utterly unacceptable. It has shaken our campus to its core and — adding to other abhorrent incidents that we have witnessed and that have circulated on social media over the past several days — further damaged our community’s sense of security," his letter read.