Large numbers of New York City police officers entered Columbia University late April 30, hours after the mayor said a pro-Palestinian protest that has crippled the Ivy League school for two weeks “must end now.”

The officers took protesters into custody after the university called in police to end the pro-Palestinian occupation on the New York campus.

The scene unfolded shortly after 9 p.m. as police, wearing helmets and carrying zip ties and riot shields, massed at the Ivy League university’s entrance. The demonstrators had occupied Hamilton Hall, an administration building on campus, more than 12 hours earlier, spreading their reach from an encampment elsewhere on the grounds that’s been there for nearly two weeks.