A criminal investigation is taking place amid allegations of inappropriate conduct between a male Tillicum Middle School teacher and a female student at another school.

The teacher resigned from the school district immediately, said Principal Dion Yahoudy in a letter to parents Tuesday.

Yahoudy said in the letter that student and staff safety is a priority at Tillicum.

“Allegations of inappropriate conduct by any adult are taken very seriously,” she said. “Parents may understandably be concerned that a teacher, a trusted adult who had regular contact with their child, is being investigated for inappropriate contact with a student.”

Yahoudy and district spokesperson Jacque Coe said they could not comment because of the police investigation.

Bellevue police were unresponsive to phone calls and e-mails Wednesday afternoon.