The conditions were right in Zion National Park (which they are in Colorado, too) to create quicksand, and a couple that was hiking found some. 

A wet winter, freezing temperatures, snow, a trail. Conditions that you can find in Colorado, that can create quicksand. I cannot imagine being stuck in it.  The story has me rethinking ANY kind of winter hikes.

From CBS News, over this weekend (February 16, 2019) a man and his girlfriend were on a hike through Zion National Park. They were on the 'Subway' trail. At one point, the girlfriend stepped into some quicksand that she didn't know was there (apparently, it can look dry on top, but then be quicksand beneath). Her boyfriend got her out, but by doing so, got his leg stuck in it, up to his hip. He couldn't get out, couldn't move.

The man's girlfriend went for help, but it wasn't until ten hours later that park rangers got to him. Two hours after that, he was freed from the quicksand; but weather forced them to stay put until morning for rescue from the area. The next morning, they helicoptered in rescue personnel who got down to where they were and got them all out.

The stuck hiker suffered some hypothermia and muscle damage but should be fine.

You can get more on the story and what to look for to avoid quicksand, from CBS News HERE.