Evergreen State College in Washington state was abruptly closed Thursday morning after officials received a "direct threat to campus safety."
"All are asked to leave campus or return to residence halls for instructions," said a statement on the college's website.
Law enforcement thought the threat via a 911 call was credible enough to forward to Evergreen State College in Olympia, and school officials decided to close the campus, Sandra Kaiser, Evergreen's vice president for college relations, told reporters Thursday.
Campus police declined to elaborate on the nature of the threat when contacted by Fox News.
Officers were "visible and present" on campus Thursday, and school officials were waiting to hear from law enforcement when they "can give the all clear," Kaiser said. She hoped classes would resume Friday.
The Olympia school became the center of controversy after activists asked white students to leave campus to talk about race issues. It's a reversal from the longstanding annual "Day of Absence," in which minorities traditionally attend programs off campus.
When a biology professor, Bret Weinstein, objected to the event, the activists demanded that he resign.
"They imagined that I'm a racist," Weinstein, who has taught at Evergreen for 15 years, told Fox News' "Tucker Carlson Tonight" last week. "That has caused them to imagine that I have no right to speak."
Evergreen State said participation in the event has always been optional.
"White students have never been required to leave campus, for Day of Absence, or any Evergreen activity," the college said.
Advocates claim the effort helps increase social awareness, but critics have called it divisive.
The Associated Press contributed to this report.