Mont. Code Ann. § 61-7-108

The driver of a vehicle who knows or reasonably should have known that the driver has been involved in an accident resulting in injury to or death of any person, striking the body of a deceased person, or property damage to an apparent extent of $1,000 or more shall immediately by the quickest means of communication give notice of the accident to the local police department if the accident occurs within a municipality, otherwise to the office of the county sheriff or the nearest office of the highway patrol.