Firefighters from Summit Fire & EMS and the Red, White & Blue Fire Protection District successfully put out a structure fire at The Enclave condo complex outside of Keystone on Friday afternoon. There were no injuries.

Firefighters from both departments responded to the fire, across the street from the River Run Village in Keystone, at about 6 a.m. after flames became visible from the roof of the complex's eastern most unit. Firefighters were initially able to go inside the unit, but structural concerns forced them outside where they removed pieces of the roof and engaged the fire.

More than six hours later, at around 12:15 p.m., firefighters were able to completely quell the blaze, said Steve Lipsher, of Summit Fire & EMS.

"It was a very tenacious fire," Lipsher said. "I'll stick by that description. It was a very complicated structure, and it took some major efforts on behalf of our firefighters to get into the interior and get this fire out."

Firefighters stuck around the scene for several hours afterward to secure the scene and make sure nobody entered the units.

Officials said that there was nobody in the condo that caught fire, though several adjacent units were evacuated. Along with the unit that caught fire, the next door unit sustained substantial damage from smoke, water and scorching, and a third unit sustained smoke damage.

In total, more than 35 firefighters from Summit and Red, White & Blue assisted in combating the fire, along with four fire engines and three ladder trucks. In response, fire and emergency crews from nearby counties arrived in Summit to assist with other calls during the fire as part of mutual aid agreements.

In addition to the fire, the incident spurred traffic backups along U.S. Highway 6 for several hours as officials closed down westbound traffic to make room for engines. Traffic was diverted down W. Keystone Road through Keystone Resort. The road opened back up at around 12:30 p.m., just after firefighters began leaving the scene, according to CDOT.

It is currently unclear what caused the fire, though Lipsher noted at this time there's no reason to suspect any foul play. An investigation into the source of the fire is underway, and will continue into next week.

"The operation between us and Red, White & Blue went flawlessly," said Lipsher. "It shows that we train together and that we work well together."