Incident Summary:

05/16/2017: Assailants shot and killed Broadwater County Deputy Sheriff Mason Moore when he attempted to pull over their vehicle along Highway 287 in Three Forks, Montana, United States. Following the shooting, additional police officers located the assailants and were led on a high-speed chase that ended at mile marker 128 in Missoula county when the vehicle was disabled. Both assailants exited the vehicle and opened fire on the surrounding officers, injuring four. The officers returned fire, killing one assailant and injuring the other assailant, who was subsequently arrested. The assailants expressed anti-police and anti-government views and discussed going on a "suicide mission" prior to the incident.



United States

North America

region/u.s. state:


Near Three Forks

Location Details:
The incident occurred along Highway 287.

Attack Information
Type of Attack (more) Armed Assault
Successful Attack? (more) Yes
Target Information (more)
Target Type: Police
Name of Entity Broadwater County Police
Specific Description Officers
Nationality of Target United States
Additional Information
Hostages No
Ransom No
Property Damage Yes
Extent of Property Damage Unknown
Value of Property Damage Unknown
Weapon Information
Type Sub-type
Firearms Automatic Weapon
Firearms Handgun
Firearms Rifle/Shotgun (non-automatic)
Weapon Details
A .308-caliber semi-automatic rifle, a Glock 9-mm pistol, and a shotgun were used in the attack.
Additional Information
Suicide Attack?No
Part of Multiple Incident?No
Criterion 1 (more) Yes
Criterion 2 (more) Yes
Criterion 3 (more) Yes
Doubt Terrorism Proper (more) No
Additional Information Broadwater County Deputy Sheriff Mason Moore was killed in the attack.
Perpetrator Group Information
Group Name Claimed Responsibility
Anti-Police extremists No
Perpetrator Statistics
Number of Perpetrators 2
Number of Captured Perpetrators 1
Casualty Information
Total Number of Casualties 2 Fatalities / 5 Injured
Total Number of Fatalities 2
Number of U.S. Fatalities 2
Number of Perpetrator Fatalities 1
Total Number of Injured 5
Number of U.S. Injured 5
Number of Perpetrators Injured 1
"Prosecutors no longer seeking death penalty in case of slain Broadwater County deputy," Helena Independent Record, July 20, 2018.
"Prosecutors: Men made u-turn to kill deputy, tried to take kids on 'suicide mission'," Helena Independent Record, May 19, 2017.
"Suspect in MT Officer's Shooting Held Anti-Government Views," Courthouse News Service, May 18, 2017.