CAMBRIDGE, Mass. (AP) — Police detained several people Thursday at the Massachusetts Institute of Technology after demonstrators blocked a parking garage in their ongoing protest movement connected to the Israel-Hamas war.

Tensions have ratcheted up in standoffs with protesters of the Israel-Hamas war on campuses across the United States and increasingly in Europe. Some colleges cracked down immediately, while others have tolerated the demonstrations. Some have begun to lose patience and call in the police over concerns about disruptions to campus life and safety.

In Boston, the U.S. city most identified with higher education, students have set up encampments on at least five campuses, including MIT, Northeastern University and Harvard University.

At MIT, protesters have been asking administrators to end all research contracts with Israel’s Ministry of Defense, which they estimate total $11 million since 2015. On Thursday, the school issued an alert just before 2 p.m. saying protestors were blocking the entrance to a campus parking garage and spilling onto a nearby street.

About two hours later, authorities split protesters up and pushed them away from the garage. At least three people were detained. Protesters walked away continuing to chant “free Palestine” after the three were detained and police pushed them back.

The pro-Palestinian protest movement began nearly three weeks ago at Columbia University New York City. It has since swept college campuses nationwide, with more than 2,500 people arrested.