The fire was reported in Erie, a northwest lake town, at about 1.15am on Sunday (local time), Chief Guy Santone of the Erie Fire Department said.
The victims ranged in ages from 8 months to 7 years, Santone said. The Erie Regional Chamber and Growth Partnership lists a daycare centre at the fire address.
Valerie Lockett-Slupski, standing across the street from the fire-damaged house, said she was the grandmother of four of the children, and that they were staying at the daycare centre because their parents were working overnight, the Erie Times-News reported.