PROVIDENCE, R.I. — A teachers’ union sued on Wednesday to block the firings of all teachers and staff at a low-performing Rhode Island high school.

The union says the teachers, who were fired from Central Falls High School in February, have not received the individual termination hearings they believe they are entitled to under state law and their collective bargaining agreement.

The union also says it believed Superintendent Frances Gallo had been committed to working with the teachers and a mediator to find an alternative to the mass firings. Instead, the lawsuit says, teachers were sent letters last week telling them that their former positions were about to be posted.

The fired teachers can reapply for their jobs, but no more than half can be hired under the federal turnaround model selected for the school.