The Trump administration is trying to strip Harvard of its ability to enroll international students — an effort blocked by a federal judge on Friday, just hours after the university filed a lawsuit claiming Trump was violating its First Amendment rights.

Fear and confusion mounted quickly on Thursday as international students, who make up more than a quarter of the university’s enrollment, sought clarity or reassurance.

On Thursday, the Department of Homeland Security had abruptly revoked the university’s ability to enroll foreign students.