Six people were displaced from their homes on Sunday following a heavy structure fire that rendered four residences uninhabitable, according to the Colorado Springs Fire Department.

The blaze took place on Armdale Heights near Dublin Boulevard and impacted two duplexes, fire officials said.

The first calls about the fire came in at about 12:30 p.m. and the first crews were on scene at 12:35 p.m., according to CSFD spokeswoman Ashley Franco.

“We called in a third alarm because there was very, very heavy fire and we needed more resources,” Franco said.

A total of 14 CSFD units and 64 personnel were on hand to battle the blaze, with assistance from Falcon and Black Forest fire departments, officials said.

Video posted on CSFD’s social media accounts showed two homes fully ablaze, with flames and heavy smoke coming through the rooftops.

“A lot of times (the firefighters) will go straight to the roof and cut some holes to make sure the fire can go up,” Franco said. “We could not do that in this instance because we had very early signs of collapse.”

Firefighting efforts were complicated by a compromised gas line in one of the homes, which fed the flames, Franco said.

“That made it really dangerous for our firefighters and made it difficult to get the fire out until we could get the gas turned off,” she said.

The fire was deemed under control at 1:27 p.m., less than an hour after the first units arrived at the scene, CSFD said.

Four homes were either badly burned or sustained significant smoke and water damage and were deemed unlivable. No injuries to firefighters or civilians were reported. Four pets that were living in the homes have been accounted for, Franco said.

CSFD and Colorado Springs Utilities were working to determine the cause and origin of the fire.