An international student in a graduate program at Tufts University was taken into federal custody on Tuesday outside an off-campus apartment building, according to the university’s president and an attorney representing the student.

The student, Rumeysa Ozturk, a Turkish citizen, had a valid student visa as a doctoral student at Tufts, according to a statement from her lawyer, Mahsa Khanbabai. Ms. Ozturk, who is Muslim, was heading out to break her Ramadan fast with friends Tuesday night when she was detained by agents from the Department of Homeland Security near her apartment in Somerville, Mass., Ms. Khanbabai said.

“We are unaware of her whereabouts and have not been able to contact her,” the lawyer said. “No charges have been filed against Rumeysa to date that we are aware of.”

A spokesman for Customs and Border Protection, which is part of the department, did not immediately respond to questions on Wednesday about the case.

Tufts administrators were told that the student’s visa had been terminated, the university’s president, Sunil Kumar, wrote in an email to students, staff and faculty members Tuesday night. He said in the email that the university was “seeking to confirm whether that information is true.”

Late on Tuesday, Judge Indira Talwani of the Federal District Court in Massachusetts ordered that Ms. Ozturk not be moved out of the state without advance written notice to the court from the government. Judge Talwani’s order said that Ms. Ozturk had asked that a judge determine whether her detention was lawful.

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