Lightning struck near the top of a more than 14,000-foot mountain popular with hikers, sending three people to hospitals, Colorado authorities said.

It is not clear if they were directly hit by lightning Sunday morning, but one hiker was in serious condition.

Rescuers and an Army National Guard helicopter responded to Mount Bierstadt, about 40 miles west of Denver, and helped some hikers get off the mountain. All those who were on the mountain made it off safely.

Eight adults were transported from the trailhead: five who refused further treatment and three who were taken to Denver-area hospitals, the Clear Creek Sheriff's Office said.

Madeleine Ripley told KUSA-TV (http://on9news.tv/1SVBafd ) that she was shocked by a strike while touching a rock.

"I felt lightning and I just started running back down and I kept going," she said.

Hiker Pete Hunter told the station that the storm seemed to build right on the mountain rather than move in from the distance.

Colorado has over 50 mountains that rise more than 14,000 feet above sea level, and some hikers try to climb as many as they can.

The summits are usually rocky and exposed, making them prone to lightning strikes when afternoon storms develop. Hikers often start early in the day so they can be off the tops by the afternoon.

Mount Bierstadt, named for the western landscape painter Albert Bierstadt, is one of the most popular to climb because the hike is considered relatively easy.