POCATELLO, Idaho (AP) — Fire sprinklers inside a southeastern Idaho nursing home did not activate when a blaze erupted over the weekend, authorities said.

The State Fire Marshal's Office and the Pocatello Fire Department are investigating the cause of the fire that destroyed the Safe Haven Care Center early Saturday, the Idaho State Journal reported .

All of the 49 patients were evacuated and several were treated for smoke inhalation, authorities said. The fire likely started in the attic of the facility and was possibly sparked by a malfunctioning light fixture, authorities said.

The facility was equipped with sprinklers but none activated during the blaze. Investigators are checking if the facility was granted an exemption that allowed the system to be inactive for the attic, said Travis Smith, assistant chief of operations of the Pocatello Fire Department.

"We are investigating why the fire suppression system didn't operate as expected," Smith said. "There is a question of whether or not the fire suppression system was turned on, and there are also some questions about whether or not the fire suppression system had some parts of it that were abandoned."

Department of Health and Welfare officials inspected the sprinkler system in August 2016, finding the facility did not maintain the system in reliable operating condition. The issues outlined in the report were later corrected, according to an inspection conducted in October 2016.

Yearly inspections by the fire department found no major issues with the system.

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This story has been corrected to show the fire broke out early Saturday, not late Saturday night.

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Information from: Idaho State Journal, http://www.journalnet.com