A fire at a Pennsylvania home operating as a day care center killed five children, according to authorities.

The fire occurred at a home in the town of Erie early Sunday morning, Fire Chief Guy Santone told CBS affiliate WSEE-TV. Fire officials said they pulled seven people out of the home, but were unable to revive the five children.

The homes address is listed on the Erie Regional Chamber and Growth Partnership as a 24-hour child care center called Harris Family Day Care, according to the network. Santone said the day care owner was injured in the fire and flown to UPMC Mercy hospital in Pittsburgh for treatment.

Four of the five children who died in the fire were staying at the day care while their parents were working overnight, their grandmother told the Erie Times-News . Valerie Lockett-Slupski said that her grandchildren were two boys and two girls.

We are all at a loss, trying to figure out how this happened, Lockett-Slupski told the newspaper.

Erie Chief Fire Inspector John Widomski told the Times-News that the fire is believed to have started in the living room area on the first floor, though investigators are still working to determine the cause of the fire.

We offer our deepest sympathies to all affected by this horrible tragedy, the Erie Fire Department posted on Facebook , along with photos of the damage.