The blaze was first reported at 3:25 a.m. in the 400 block of Mercer Street, and firefighters arrived to find heavy flames inside one of the homes.
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Three vehicles had also caught fire outside the building.
Fire officials say the flames spread across a narrow alleyway to the home next door and to other structures before crews could get the upper hand.
It took them about an hour to get the situation under control.
Eyewitness News is told everyone in the homes got out safely, and no injuries were reported.
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Investigators are working to determine what sparked the blaze.
The Red Cross is assisting displaced residents with food, clothing, and temporary housing.
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