FORESTHILL (CBS13) – The fire in Tahoe National Forest continues to grow slowly as firefighters make more progress containing the blaze.

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The latest update from officials states the American Fire has grown to nearly 17,000 acres and is 60 percent contained.

Nearly 1,900 fire personnel continue to hold and improve established containment lines. Wednesday night a low intensity burn was started to strengthen containment lines. Officials say aggressive fire suppression efforts have helped limit the fire’s movement along the North Fork of the Middle Fork of the American River.

Firefighters are making progress on the steep and hazardous terrain by attacking the fire directly where possible.

The American Fire has burned four structures.

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Robinson Flat Campground and Duncan Peak Lookout remain closed. Foresthill Road is closed from Humbug Canyon Road to Robinson Flat Campground.

French Meadow Reservoir and access to the Oxbow Middle Fork American Rafting Launch remain open.

Officials estimate the fire will be fully contained by September 1.

The cause of the fire is still under investigation.

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Smoke continues to spread to the surrounding areas and remains a health issue.