The University of Michigan was still without internet Wednesday morning as officials continue to investigate a “significant security concern.”

U of M shut down the school internet Sunday afternoon after an unspecified security concern was uncovered. The school has offered very few details about what the concern is.

A cybersecurity expert told Bridge Michigan that there have been 56 ransomware incidents at postsecondary institutions this year alone. Wednesday was the third day of fall classes, and university officials reported that progress was being made.

There’s no word about any possible data being stolen, or whether the security concern was related to a cyberattack on the U of M hospital system earlier this year. There’s also no word as to whether the security issue was considered criminal in nature.