DETROIT – Nearly all public schools in Detroit were closed on Wednesday as teachers called in sick to protest conditions, the school system and teachers’ union said.

It was the second time in as many weeks that teachers staged a protest. A sickout on Jan. 11 closed 64 schools.

All but nine of the district’s 97 schools were closed, leaving 44,790 students out of class, district spokeswoman Michelle Zdrodowski said.

Union officials have said teachers are frustrated over conditions in schools such as crumbling walls, mold in classrooms, rats, and too many students per class.

Detroit Public Schools, which are under state oversight, have seen declining enrollment as the city’s population decreased and heavy pension and debt obligations that have left the district in danger of running out of cash in April.

The district said on Facebook that staff members were expected to report to work as usual. “When teachers decide not to come to work, we have no other option but to close the schools,” Zdrodowski said.

The Detroit Federation of Teachers said on its website that members who did not call in sick should report to work, whether or not their schools were closed.

A report by Citizens Research Council of Michigan, a nonprofit public affairs group, said Detroit schools have $3.5 billion in debt and need to be rescued by the state of Michigan.

Teachers protested outside of the Detroit Auto Show on Wednesday evening where Obama appeared to give a speech. 

Despite speculation that the sickout would continue into the week, schools reopened on Thursday.