MADISON, Wis. -- Madison fire investigators have ruled that a late-afternoon house fire on South Hancock Street on Wednesday was accidental.

Madison Fire Department officials said that they believe the fire began with a resident burning pizza boxes and mail in the fireplace. They said the remaining debris was pushed down a chute in the fireplace and landed on debris in the basement, where the fire began. The chute had no cover installed in the basement, officials said.

The flames quickly shot up the walls and into the attic.

The house's residents weren't home and when they arrived back, they found thick smoke coming from the building's garage. They were able to save their dog, who was in the home, WISC-TV reported.

Officials said that they believe the house's construction led to the fire spreading as it did.

"Because of the balloon construction, the older style house, the fire had gone up the wall, up into the attic of the third floor. They had heavy fire up there," said Jim Keiken, assistant chief at the Madison Fire Department.

Fire officials said that newer homes have fire stops to prevent this type of blaze from spreading upward.

The blaze caused about $150,000 in damage.