Eastern Michigan University in nearby Ypsilanti also was buckling down for the storm.
"We put out an all-campus notice to students to take cover, and a tornado warning is in effect," school spokesman Walter Kraft said.
The notices were sent out via text messages and emails, Kraft said.
University of Michigan Health System spokeswoman Kara Gavin said patients were moved into hallways and window blinds were closed in rooms.
Gavin said there were no reports of damage in or around the Ann Arbor hospitals.
The American Red Cross of Washtenaw and Lenawee counties expected to open a shelter at Mill Creek Middle School in Dexter and provide shelter, food, water, other basic needs and mental health services, spokeswoman Jenni Hawes said.
"I'm sure a lot of people are pretty distraught," she said. "If you know people affected, encourage them to the shelter and get assistance."
Hawes said a second shelter opened nearby in Ann Arbor, where significant flooding forced the evacuation of an apartment complex
IMAGES: Storm Damage in Dexter