PHILADELPHIA (CBS) — Flames tore through three vacant row homes in Philadelphia’s Strawberry Mansion neighborhood early Tuesday.

Officials say the fire happened around 3:30 a.m. on the corner of North 29th and Diamond Streets.

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As of 8 a.m., firefighters were still on the scene dealing with some hot spots.

One of the homes also had a partial collapse in the rear of the building.

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The Philadelphia Fire Commissioner says all three homes were abandoned, but a full, thorough check will be done to make sure no one was trapped inside.

“We haven’t done a full secondary search. We always do a primary search…during the initial attempt, we didn’t encounter anyone inside, but we haven’t done a secondary one,” he says.

Thus far, no injuries have been reported. The cause of the fire is under investigation.

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The Red Cross says it is assisting three families.