Some evacuations have been ordered as the North Delphia Fire has burned around 2,000 acres in Musselshell County.
There have been no reports of any injuries as of Friday afternoon.
The North Delphia Subdivision has been evacuated and approximately 120 people are fighting the fire, according to Disaster & Emergency Services coordinator Adam Carlson.
The American Red Cross has set up a shelter at the Roundup Community Center for people being evacuated.
Livestock can be taken to the Musselshell County fairgrounds.
Firefighters are working to protect structures and slow the fire progression.
The fire started near Buckhorn Drive north of the North Delphia Subdivision on Friday morning by lightning strikes, and grew rapidly.
Crews were responding to other area fires caused by the same storm, so there was some delay in their response to the North Delphia Fire.
Several aircraft have been brought in to fight the fire as smoke settles into the Bull Mountains.
Agencies responding include the MT Department of Natural Resources & Conservation, the U.S. Bureau of Land Management, Bull Mountain Fire, Roundup Fire, Hawk Creek Fire, and Melstone Fire.
As the fire moves toward Highway 12, Musselshell County Sheriff's deputies are implementing traffic restrictions.
Law enforcement plans to close Highway 12 East from mile markers 182 to 186, according to DES.
People are asked to stay out of the area.