A man was arrested on the University of Michigan’s central campus Thursday morning after authorities say he pulled a knife on a woman near a loading dock off South Division Street.

The woman escaped uninjured, Department of Public Safety spokeswoman Diane Brown said, and police do not see a connection to a string of recent attacks on women around Ann Arbor.

“We strongly believe robbery was the motive and it’s not in any way connected to the assaults,” she said.

Police responded to a loading dock at U-M’s Institute for Social Research around 7:45 a.m. after a woman reported she was threatened by a man with a knife. She escaped to her vehicle near the dock to call 911.

Responding officers were able to locate and arrest the man within 20 minutes, based on a description given by the woman, Brown said.

The woman was an employee of a contracting service the university uses and was not a student, Brown said. The man was not affiliated with the university.

Nothing was taken from the woman in the early morning encounter.

Brown said a crime alert was not issued to the university community because an arrest was immediately made and there was no threat to students or faculty.

Heidi Fenton covers police and courts for AnnArbor.com. Reach her at heidifenton@annarbor.com or 734-623-4673. You also can follow her on Twitter or subscribe to AnnArbor.com's e-mail newsletters.