LOVELAND, COLO. (AP) -- Authorities are investigating how a single-engine aircraft went down west of Loveland, killing one person and causing a small grass fire.

The National Transportation Safety Board will be at the scene of the crash Tuesday to determine what happened. Authorities say the aircraft went down in a rugged, mountainous area near Carter Lake west of Loveland Monday afternoon. Loveland Fire and Rescue Division Chief Merlin Green says authorities didn't immediately know how many people were on the aircraft and officials did not say whether others were injured.

The small fire was extinguished shortly after the crash.

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