ROCHESTER, Mich. - Professors at a suburban Detroit university went on strike Thursday, forcing the school to cancel classes indefinitely for about 18,0000 students.

Oakland University was to begin its fall semester on Thursday, but the teachers' union authorized a strike Wednesday night.

The union, which represents 450 faculty members at the public four-year institution, said it decided to strike after the university proposed a three-year wage freeze along with cuts in health-insurance benefits.

"It was not something we wanted to do, because we are concerned about the welfare of our students," nursing assistant professor Sharon Mills-Wisneski said while standing on the picket line outside just outside the Rochester campus. "But it was something that needed to be done."

About 25 people carried signs reading, "We'd rather be teaching," "better contract

better education" and "administration raises: your taxes at work."

Contract talks under way for months have failed to produce a deal.