MINNEAPOLIS (WCCO) — Minneapolis fire crews battled a big blaze at a duplex in the midst of high heat and humidity Saturday afternoon.

Officials say the three-alarm fire was at a three-story building on the 3200 block of Colfax Avenue South.

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It is not clear where the fire started, but it spread to all three floors of the building. Firefighters cleared the building just before 4 p.m., and there have been no reported injures so far.

Smoke from the fire could even be seen by beach goers on Lake Calhoun.

(credit: Jason Yaman)

(credit: Jason Yaman)

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Crews worked to stop the heavy fire from spreading to a nearby residence.

Firefighters were rotating in and out of the battle due to the Saturday’s scorching temperatures. Hennepin County’s Emergency Medical Service was at the scene to give firefighters cold, wet towels and to check their blood pressures.

Authorities say four firefighters were treated for injuries at the scene. Three were treated for heat exhaustion and another suffered an electric shock. All four firefighters are expected to be okay.

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The Minneapolis Fire Department was clearing up the scene by late Saturday afternoon. There were no additional reports of injuries, and the cause of the fire is under investigation.