Several apartment units were damaged following an extra-alarm fire at the Little Fort Apartments, 520 North Genesee Street in Waukegan, early Tuesday morning. | Photo: Tri Cey

Residents were evacuated and three people were transported to the hospital after an extra-alarm fire broke out in a five-story apartment building in Waukegan early Tuesday.

The Waukegan Fire Department and Waukegan Police Department were dispatched just before 1:30 a.m. Tuesday to the Little Fort Apartments, 520 North Genesee Street in Waukegan, for a reported structure fire.

Firefighters arrived to find flames and smoke showing from the top floor of the building.

Heavy flames poured out two windows on the top floor.

The residents of the building, which has approximately 100 units, were evacuated.

At the time the fire broke out, temperatures were below zero.

The Mutual Aid Box Alarm System (MABAS) was activated to the second alarm level for additional fire departments to assist.

Nearly a dozen fire departments responded to the scene.

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Paramedics transported three injured people to the hospital, fire officials said. Their conditions were not known.

Several of the units were damaged by the fire, smoke and water.

Some residents were allowed back into the building approximately an hour after the fire started.

The cause of the fire remains under investigation by the Waukegan Fire Department.