Officials on Friday said fireworks that had been shot off outside an Indiana Street residence smoldered and then ignited a couch on the porch and eventually destroyed the home.

Firefighters were called about 5 a.m. Thursday to the house at 1005 Ind., which had been converted into apartments.

According to Lawrence-Douglas County Fire Medical Chief Mark Bradford, occupants of the home “were throwing fireworks in and around that couch. It acted like a smoldering cigarette. It sat there and smoldered for a period of time until it turned into an open flame.”

The cause was determined based on evidence and interviews, Bradford said. Bradford couldn’t confirm how many of the occupants were involved with shooting off fireworks, saying the investigation was continuing. He did say numerous people had been at the house early Thursday before the fire. Four men, the occupants of the house, were in the house at the time of the fire, and all escaped.

Bradford said a “short period of time” passed between the time the men went inside the house and when the fire was reported at 5 a.m., Bradford said. The fire caused $360,000 in damage and destroyed the house.

“Any time anybody uses combustibles near ignition sources of any sort, a couch or cardboard boxes, a wooden deck in general, extreme caution needs to be used, and it’s quite frankly just not a good idea,” Bradford said.

Often fires are started when an ignition source has been left unattended on or near a combustible, Bradford said. Cigarette butts in a house or a grill on a wooden deck, for example, are common incidents, he said.

“Routinely, these types of incidents go unnoticed,” he said. “Once it’s in free flame, there’s no stopping it.”

“If you’re out there, you can quickly report it or extinguish it.”

In this case, the fireworks were shot off illegally.

“People need to understand we have an ordinance that permits the use of certain type of fireworks : other than what is permitted by code or permit, and they didn’t have either,” he said.

Three people were treated for injuries from the fire.

Sam Buhler, a Kansas University senior from Lawrence, was transported to Kansas University Hospital in Kansas City, Kan., for injuries he suffered from jumping out of the third story of the house to escape the fire. The hospital could not provide details on Buhler’s condition. But Thursday night, his father, Mark, said Sam had suffered smoke inhalation, had injured a knee severely enough to require surgery and had several cuts.

Another occupant of the house was treated at Lawrence Memorial Hospital for smoke inhalation and later released.

A firefighter also was treated at the LMH for non-life-threatening injuries.