STORY: Officers entered the Portland State University library on Thursday morning, where demonstrators had barricaded themselves since Monday (April 29). Several dozen protesters ran out of the building as a phalanx of officers in riot gear rushed over to arrest them.

Police made more arrests later on Thursday night as demonstrators attempted to retake it. A university spokesperson described it as a "very fluid situation."

The protests across U.S. universities follow the deadly Oct. 7 attack on southern Israel by Hamas militants from the Gaza Strip, which killed 1,200 people and saw dozens taken hostage, and an ensuing Israeli offensive that has killed about 34,000, according to Palestinian authorities, and created a humanitarian crisis.