COLORADO SPRINGS, Colo. (CBS4)- The investigation into what caused Colorado’s most destructive wildfire continues as authorities examine video.

The Waldo Canyon Fire was human caused on June 23. Whether it was accidental, negligence or a deliberate act has yet to be determined.

The fire destroyed 346 homes, burned 17,659 acres and was 45 percent contained Sunday morning.

A cycling group from Carmichael Racing in Colorado Springs was nearby when the fire began. They were told to get out and get out fast.

“From what we saw to the size it has grown I never imaged it would be as big as it is,” said Carmichael Training Coach Jane Rynbrandt.

The video she took of the fire as the group made their way down the mountain is being examined by investigators. Some of the clues indicate the fire is burning in a remote area with some trails. There was no lightning in the area at the time.

“When we were up in the area it was a beautiful blue day. We were stopped there on our way to Rampart Reservoir and stopped and took pictures,” said Rynbrandt.

Because of that investigators believe the fire was not caused by an act of nature but rather by humans. How and why remain a mystery.

“The U.S. Forest Service has brought in a cause and origin specialist,” said El Paso County Sheriff’s Office spokesman Jeff Kramer.