School officials called police and put a Minnesota high school on lockdown as tensions boiled over after racist comments targeting black students were posted on social media.

Two students accused of assaulting an officer were arrested amid the altercation this week at Owatonna Senior High School.

School district officials say they began investigating after a derogatory comment was posted Sunday by a student. District spokeswoman Shay Baumbach says tensions escalated Monday at lunchtime, when another student posted a similar comment on social media.

Baumbach says both posts were directed at black students in general. She says school officials intervened after getting word that some students planned to confront the student who made the Monday post. Increasing tension prompted administrators to lock down the school and call police.

Owatonna is about 60 miles (96.5 kilometers) south of Minneapolis.