Published: May 03, 2014 8:07 PM EDT

ANCHORAGE, Alaska (AP) - Authorities say a 19-year-old man shot and killed two Alaska state troopers from behind with an assault rifle as they struggled to arrest his father.
    
Prosecutors in Alaska charged Nathanial Lee Kangas of the remote village of Tanana with two counts of first-degree murder on Saturday for the deaths of 26-year-old Trooper Gabriel "Gabe" Rich and 45-year-old Sgt. Patrick "Scott" Johnson.
    
Rich and Johnson, who were not based in the interior community of 238 people, had traveled to Tanana to arrest Kangas' father, Arvin, on charges of driving without a license and threatening the village's unarmed public safety officer.
    
Authorities say the troopers were talking to Arvin Kangas outside his home when he tried to escape inside. The troopers pursued, and a scuffle ensued. Authorities say that as the men were struggling, Nathanial Kangas shot the troopers.

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