Cell phone video shows a kayaker lose control over Great Falls, leading to a scary rescue. Image courtesy of Brad Beauregard.

VIDEO: Potomac Rapids Rescue Highlights River Danger

Three kayakers saw the power of Great Falls, on the Potomac River about 14 miles above Washington, D.C., as one of them was nearly swept away in the rapids. With help from his friends, the paddler survived. Cheryl Costello has the cautionary tale from the mighty Potomac, where water speed can reach 30 miles per hour. Watch below: