07/20/2011 10:46 am ET Updated Sep 19, 2011

Yosemite National Park Searches For Hikers, Feared Swept Over Falls

Park officials began a search at Yosemite National Park on Tuesday afternoon for hikers who may have been swept over the park's falls.

According to the Associated Press, Yosemite officials received multiple emergency calls on Tuesday from witnesses who saw one or more hikers go into the water and over Vernal Falls, which is 317 feet high. At the top of the path to Vernal Falls, a guardrail seperates Yosemite visitors from the water, and yet accounts suggest that 13 people have fallen over and died since records began.

Witnesses provided various reports of what happened to Yosemite officials and reporters.

Witness Jacob Bibee told CNN affiliate KGPE-TV, “I saw the man’s eyes when he went over the falls. That was devastating."

Witness Dean Sabo told KGPE, “I saw two that were holding each other and one that was floating alone through the water. And the reason that I looked was because this woman was screaming, running along the edge of the water."

NBC Fresno affiliate KSEE reports that, according to witnesses, a man and woman climbed over the guardrail for a better view, and possibly encouraged their children to go over as well. The man and woman began to slip before the children climbed over. Another man jumped over the guardrail to help, but also fell over the edge, KSEE reports.

Park spokeswoman Kari Cobb said that rangers quickly shut down Mist Trail, and searched the Merced River corridor for any possible victims. While the search was stopped when darkness fell, it is expected to resume today.

In June, two hikers died after falling into the Hetch Hetchy Reservoir at Yosemite National Park.

According to the Associated Press, record snowfall has created "breathtaking" waterfalls at Yosemite, and the park carries great beauty, from lunar rainbows to meditative cascades. But there are dangers involved, and visitors don't realize the slippery trail conditions or the force of the water, especially given the additional snowfall.

Record weather has been seen around the globe this year, from snowfalls to heat waves. In June, Rajendar Pachauri, chairman of the U.N. Intergovernmental Panel on Climate Change, announced that they would release a report in November studying the link between climate change and extreme weather events.

UPDATE 2:12pm-- Jake Bibee told the Associated Press in a news update that he saw a man on the far side of the safety railing holding a screaming girl as another girl took their picture. Two more people crossed the barricade to pose for photos, and the woman slipped and fell. A man and another women fell in, trying to help.

UPDATE 3:03pm-- The hikers are now presumed dead.