CLEAR CREEK COUNTY, Colo. (CBS4) – Two Denver-area women suffered serious injuries Saturday in an area of established climbing routes in Clear Creek Canyon. Authorities closed part of Highway 6 after fire trucks, ambulances, a medical helicopter and rescue personnel responded to the scene and required use of all lanes of traffic.

Emergency crews were notified of the incident at about 10:15 a.m.

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According to Capt. Ben Moline of the Golden Fire Department, a man was climbing one of the many routes east of Tunnel 2. He was about 30 feet above one of the women who was on belay, or supporting his ascent with a safety rope. As the man grabbed and pulled his way up, a large “person-sized” rock, as described by witnesses, came loose and fell.

It struck the ground near the woman and shattered. One of the flying pieces struck the woman on the head. She wasn’t wearing a helmet.

Another female climber, standing nearby but not actively climbing, was hit in the foot.

The man was uninjured.

(credit: CBS)

“This was honestly a kind of fluke accident,” Moline told CBS4. “The rock formations just change over time. We’ve had a lot of rain recently, and it was hot today. The rocks expand. We believe that’s what happened today.”

Moline acknowledged the climbers were fortunate the boulder did not directly land on either of the women.

“They got lucky with where the rock fell and how it broke into pieces,” Moline said. But, he added, “The climbers did exactly what they needed to after the accident.”

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(credit: CBS)

Moline said the accident occurred just east of Tunnel 2 on rock formations popular with intermediate and advanced rock climbers. He said the area has 15-20 established routes.

The fire department’s ladder truck raised a bucket to meet rescuers and their patients midway up the slope. It’s a maneuver that Moline said they’ve used more than once in this very spot. It is quicker than setting up a rope system and safer, too, Moline stated.

(credit: CBS)

The women, both 37 years old, were taken to St. Anthony’s Medical Center.

The Colorado State Patrol shared video of Flight For Life helicopter lifting off with the woman with the head injury.

(credit: Colorado State Patrol)

A second climber was also rescued about 30 minutes later. She was taken to St. Anthony’s as well but by ambulance.

(credit: CBS)

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U.S. 6 was closed in both directions between CO 119 and CO 58. The highway reopened at around 1:30 p.m.

Danielle Chavira