[What you need to know to start the day: Get New York Today in your inbox.]

Students arrived at Ethical Culture Fieldston, one of New York City’s most prestigious private schools, early Monday to find one of their classroom buildings locked. On the other side of a set of blue doors stood classmates who had barricaded themselves inside, protesting what they said was a racist culture that Fieldston’s leaders had not done enough to reform.

By Monday night, some students were curled up in sleeping bags. On Tuesday, they were occupying the building for a second day as the head of their school was in crisis mode, trying to work with students and parents to end the lock-in.

Tensions at the school’s sprawling Bronx campus had been building for weeks, after a video of students using the word “crack” followed by a racial epithet was shared among students and eventually seen by administrators. The video was created several years ago.

The administrators sprang into action after viewing the clip. Of the five students in the video, one had withdrawn from school, the school said. Three others were disciplined, and one student, who appeared unconscious in the footage, was not. None of those four students has returned to classes.