A green-waste landfill fire sent smoke across the Tucson area on Sunday morning, the Tucson Fire Department said .

The landfill, on East Drexel Road near South Houghton Road, started burning about 3 a.m., said Capt. Nick Janton, with TFD.

Officials said the fire could burn for several days and the cause has not been determined.  No injuries or threatened structures were reported.

"There is smoke throughout the Tucson valley from this fire that can cause susceptible populations to have respiratory irritations," Janton said. Fire officials have warned area residents in the area to stay indoors, as the smoke was expected to be heavy.

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The fire was being fought by crews from the Tucson, Davis-Monthan and Rural Metro departments.