MINNEAPOLIS (WCCO) – Three mailboxes exploded in Crow Wing County on Sunday, and two of the explosions started fires.

Police believe fireworks were placed in the mailboxes, and a juvenile has been arrested.

A grass fire was put out by the Brainerd Fire Department on the 9000 block of 50th Avenue around 11 a.m. Sunday. Another fire started on the 5000 block of Sweet Road.

The Crow Wing County Sheriff’s Office is continuing its investigation and expects to identify more suspects.