Photos: 6-Alarm Fire Rips Through Fort Worth, TX, Apartment Building

Hundreds were displaced Monday as a six-alarm fire challenged Fort Worth firefighters as it burned on and below the roof of a sprawling apartment complex.

Nearly half the city's fire companies responded at the height of the blaze, which firefighters fought as real-feel temperatures hovered around 100 degrees. They remain on scene Tuesday morning, hitting hot spots.

Firefighters were called around 1:45 p.m. for a air conditioner unit on fire and Engine 8 found smoke coming from the roof, Fort Worth Fire Department Spokesman Craig Trojacek told Firehouse.com.

"They did find fire in the roof, around the air conditioning unit," Fire Chief Jim Davis said.

The two-building complex, The Cooper, located just south of downtown Fort Worth, has 390 units. The five-story building has a rooftop penthouse on one side.

About two dozen firefighters used saws to cut open the roof and expose the spreading fire but they were challenged.

Davis said firefighters worked to open the roof but the rubber membrane slowed their efforts to expose fire.

"The roof did exactly what it is supposed to, to keep the water out of the building," said Davis.

He showed drone footage of the fire, which was spreading beneath the roof.

A trench cut was also performed to slow the spread of the fire.

At the height of the fire, five aerials were placed to the roof of the building, either flowing their elevated master streams, or being used a flying standpipe to provide hoselines on the roof.

Trojacek said parts of the roof collapsed during the fire fight, making it dangerous for inside crews to work.

Within three hours, over 40 fire companies - nearly half the city's fire resources - were at the scene, plus firefighters from River Oaks and Lake Worth.

"We continued to rotate our crews into the building throughout the day and night due to the high temperatures," Trojacek said. "They were taking a beating in there, so we would cycle them through and have them come outside to rehab to hydrate and cool down."

A few firefighters were injured, mostly suffering from heat exhaustion.

Throughout the day and into the evening, firefighters located dozens of pets and returned them to their owners.

At one point, citizens brought case of sandwiches from a nearby Firehouse Subs to hand out to exhausted firefighters.