Four people died and one person was injured early Tuesday in a house fire in Memphis, authorities said.

Firefighters responded to the one-story home around 2 a.m., Memphis Fire Department spokeswoman Qwanesha Ward said in a news release.

Two adults and two children were killed the blaze, which was caused by a space heater in a rear bedroom, Ward said. Officials didn't release their names, but said the children were 8 and 10 years old and the adults were 33 and 62.

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A fifth person found in the home was taken to a hospital in critical condition. It was not known if the house had a smoke alarm, the news release said.

"This situation is sad. I just want to urge the community to be mindful when using space heaters, and never leave them unattended," Ward told media outlets.