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One person was arrested after a fire started underneath Seattle's Alaskan Way Viaduct, creating heavy smoke that shut down traffic on SR 99 Sunday afternoon.

Seattle Fire Department said the brush fire broke out the 1900 block of the Alaskan Way Viaduct and quickly engulfed a nearby homeless encampment where several people had pitched their tents.

Around 20 tents were in the burn area, which measured around 300 feet by 300 feet.

Nearby railroad tracks were closed as the fire spread. Within minutes, firefighters quickly put out the flames and were putting water on remaining hot spots. The railroad tracks have since reopened.

People were evacuated from the area and no injuries were reported.

Officers arrested a man who witnesses claimed set the fire. Officers booked him into King County Jail for investigation of arson.

Seattle Department of Transportation officials plan to inspect the underside of the viaduct for any structural damage caused by the heat.

At the same time a few blocks away from the brush fire in a separate incident, a mini van was engulfed in flames in the Belltown neighborhood. Fire officials say there's no indication the van fire was related to the brush fire.

A viewer caught the dramatic car fire on video.

Other viewers were also capturing the smoke from the fires on video and sharing it on social media.

A post shared by Armin H. Ausejo (@arrrminhammerrr) on


So there's a fire under the viaduct! Crazy smoke @king5seattle

A post shared by Armin H. Ausejo (@arrrminhammerrr) on

KING 5's Liza Javier and Ted Land contributed to this report.