Then she heard a piercing scream. She rushed outside.

The two boys — Ms. Harris’s 12- and 17-year-old sons — survived by leaping from the second floor.

“We were screaming at the kids to jump down,” Ms. Scott said. “They were really scared.”

The 12-year-old boy was covered in soot, Ms. Scott said. The windows started blowing out.

“It sounded like four mini-explosions,” she said.

Chief Santone, who was previously the city’s fire inspector, said that fire safety officials regularly check for smoke detectors at day care centers but that he could not recall visiting this one before. The chief said it was hard to tell if the detector in the attic had been working but that he “highly doubted it.”

“They’re supposed to have the correct number of smoke detectors, which they did not,” he said.

Every bedroom should have a smoke detector, as well as the hallway outside the bedrooms, the first floor, the basement and the attic, Chief Santone said. Erie County property records show that the house had five bedrooms.

The chief said that investigators were looking at an electrical malfunction as the possible cause of the fire and that fans, lights and chargers had been plugged into several extension cords running under a couch.

An electrical engineer is expected to check the house as early as Monday, he said.

The day care center had its certificate of compliance renewed by the state on March 21, according to a state database. The certificate is valid for one year.