CALISTOGA (CBS SF) — An inspection helicopter clipped high-intensity power lines near Calistoga Thursday, starting two small brush fire and triggering a massive power outage that stretched from northern Napa County to southern Sonoma County, officials said.

The Bell 206-L4 helicopter was forced to make a precautionary emergency landing and none of the three passengers aboard suffered any injuries.

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Two small blazes erupted below the towers but was quickly extinguished by local firefighters. The helicopter was registered to a Redding company and was inspecting power lines.

The fires burned a half-acre and 1 acre, Cal Fire spokesman Will Powers said.

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The area is near Tubbs Lane where the Tubbs Fire started on Oct. 8, 2017, and spread rapidly to Sonoma County.

Pacific Gas & Electric said 3,841 customers were without power including the towns of Calistoga, Kellogg and Woodleaf.

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Crews estimated power would be restored by 4:15 p.m. The FAA said it would investigate the incident.