MUKWONAGO, Wis. (CBS 58) -- The Mukwonago Area School District sent a letter to parents sharing a parent boarded a school bus with a firearm. 

The letter was sent to families and staff on Monday, March 3. 

The letter says on Feb. 26, a parent from Section Elementary boarded a bus due a personal safety concern and it was discovered through an investigation by the Mukwonago Police Department the parent was in possession of a lockbox that contained a firearm. 

According to the school district, the weapon remained in the lockbox and was not removed at any time on the bus. 

The district says they are meeting with the bus company, Dousman Transport, to reestablish protocols regarding non-students and non-staff riding the bus. 

View the full letter to parents here.