Columbia University has announced that four of its students arrested during a sit-in earlier this week, where they voiced support for fellow students expelled over pro-Palestinian activism, have been suspended, Al Jazeera reports.

“These students have been suspended and restricted from campus as we swiftly work through the discipline process,” the university’s administration said in a statement.

Protests were held this week at Columbia University-affiliated Barnard College in New York, where demonstrators occupied a library as they called for three students expelled for their pro-Palestine activism to be reinstated.

New York police cleared out the Milstein Library hours after the demonstration began, claiming they had received a bomb threat in the area.

At least nine students were arrested.