Firefighters who believed they had put out a North Durham apartment fire Monday night were called back early Tuesday when the blaze rekindled and damaged it and five adjoining units.
The fires were at 229 Rippling Stream Road, where officials said the first fire appeared to have been started by cooking.
Deputy Chief Chris Iannuzzi said the first fire was brought under control in about 10 minutes by firefighters who got the call at 10:08 p.m.
Trucks were called back to the two-story building at 1:29 a.m., about 45 minutes after the last crew had left the scene.
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Red Cross workers, who were helping people displaced by the first fire, saw flames coming from the attic that stretched across the building.
That fire wrecked the roof, and that resulted in water damage to the five apartments that had been saved in the first blaze.
Iannuzzi said investigators discovered that smoldering debris from the first fire had fallen into a heating duct that was behind an intact wall of the first apartment.
That resulted in heat or embers reaching the attic space and starting the second fire, Iannuzzi said.
No one was hurt in either fire, but the Red Cross was helping 20 adults and six children Tuesday morning.