For years, hundreds of foreign students enrolled in a seemingly legitimate Detroit-area university that suspiciously lacked classes, professors or a formal campus. But the University of Farmington still managed to offer immigrants something valuable: proof that they were enrolled in a full-time university so they could stay in the U.S. and work on a student visa.

At least, until the university was revealed to be an elaborate sting operation carried out by undercover agents with Immigration and Customs Enforcement.

On Wednesday, federal agents arrested eight people who were recruiting students to the University of Farmington and arrested dozens of students for participating in what attorneys are calling a nationwide pay-to-stay scheme, according to the Detroit News. Many of those arrested are from India, and the students allegedly wanted to participate in a student visa program called CPT, or Curricular Practical Training, which allows students to work in the U.S. while they work toward a degree. The eight recruiters were arrested on charges of conspiracy, immigration fraud and helping to enroll the students in exchange for cash and kickbacks.

It’s not yet clear exactly how many students were arrested or what charges they might face, but, according to the Detroit Free Press, a group representing Americans with roots in Telugu-speaking parts of India said 100 students have been arrested or are facing arrest warrants.

The university was set up in 2015, according to court documents, and operated by undercover federal agents who started posing as staff between May 2017 and January of this year. The special agents were employed by Homeland Security Investigation, the investigative arm of ICE.

The fake university, which boasted a stereotypical college website featuring stock photos of coffee-sipping students, was in reality located in an office park in Farmington Hills, a Detroit suburb. Students could contact recruiters and pay thousands of dollars to achieve evidence and fraudulent paperwork stating that they were enrolled in a full-time program, despite doing none of the work such a program might require. Students allegedly were aware the scheme was illegal, according to a series of indictments filed in the U.S. District Court for the Eastern District of Michigan on Jan. 15 and unsealed Wednesday. The Department of Homeland Security lists the University of Farmington on its website displaying certified schools for international students.

Together, the eight recruiters for the school brought at least 600 students to the school, allowing them to remain in the country on student visas. They now face federal conspiracy charges.

“Each of the students who ‘enrolled’ and ‘made tuition’ payments to the university knew that they would not attend any actual classes, earn credits or make academic progress toward an actual degree in a particular field to study — a ‘pay to stay scheme,’” attorneys allege in the indictment.

Many of the students involved with the fake university entered the U.S. legally on F-1 visas after they were accepted to legitimate schools, and then transferred to the University of Farmington, according to WXYZ.