PHILADELPHIA (CBS) — Fire ripped through four homes overnight in Port Richmond.

Flames broke out around 1:45 a.m. Monday inside a vacant row home in the 2900 block of Memphis Street and quickly spread to three neighboring homes.

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A family inside one of those burning homes was awakened by a neighbor who came outside, saw the flames and began banging on their door. The two adults and two children inside got out safely and were being assisted by the American Red Cross.

Officials say three other homes damaged by the fire were vacant.

It took firefighters about 30 minutes to contain the blaze.

Investigators were working to determine the cause of the fire. Some neighbors believe it’s suspicious because the house where the fire started had been boarded up and was on fire before.

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“It must have been (set) intentionally,” said one neighbor. “It can’t be no other explanation. The house is boarded.”

They say there have been three fires in the neighborhood in the past six months.

“It was worse than last time,” said another neighbor. “The last time, I had time to come out. This time, I had to come running, no shoes, no jacket, nothing.”

Fortunately, no one was injured in the fire.

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The fire marshal did not offer any immediate word on whether the fire was being investigated as an arson.