A heater unit is believed to have caused a house fire Tuesday in the westernmost part of the city of Houston, just outside Missouri City, Houston Fire Department officials said.

All four people living in the home, in the 15100 block of Chase Ridge, got out safely, HFD District Chief Jeff Boles said. Some pets might be unaccounted for, however, and one cat died.

The family woke up in the night because they heard their smoke detectors go off, and Boles advised that now is a good time for other families to make sure their own devices are working.

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“When you change your clocks, you always remember to change your nine volt batteries,” Boles said. “This is a great reminder to do that – (it) saved this family’s life.”

Kay Kelly, who lives in the home, said she doesn’t think she and her family would have woken up if it weren’t for the smoke detectors.

“We never thought we’d need them, but thank God we had them,” Kelly said.

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Kelly said a furnace was on in the home.

Much of the fire was burning on the attic and second floor, but firefighters were able to snuff out the fire in the attic quickly, Boles said.