July 21, 2011 -- As family and friends await the discovery of three hikers who were swept over a 317-foot waterfall in Yosemite National Park Tuesday, the three friends' presumed deaths are a reminder that when visiting parks and other nature sites, safety is key.
"Read any safety bulletin you see," said Jeffrey Olson, spokesman for the National Park Service, which oversees Yosemite. "When we put up railings at edges of places where it's obviously a long way down ... we put those railings up for a reason. We want you to return again."
On Tuesday, Hormiz David, 22, of Modesto, Calif.; Ninos Yacoub, 27, of Turlock, Calif.; and Ramina Badal, 21, of Manteca, Calif., were on a church group outing at Yosemite when they climbed over a metal barricade on the Mist Trail.
"They went over the barricade and were playing in and around the water," Scott Gediman, a spokesman for Yosemite, told KFSN-TV.
Gediman said there was a sign saying "Danger" with a stick-figure person in midair.
"Apparently, they were taking photos, playing in the water," Gediman said. "One of the males lost his footing, started to slide down, the second male tried to rescue him and also lost his footing. Then the third person, the female, did. Unfortunately, it was a chain reaction of events."
They were swept over the Vernal Fall and into the Merced River.
Kari Cobb, a park spokeswoman, said the victims' bodies might not be found until the river's waters recede later in the year.
"They were honest, righteous Christians trying to live their lives the right way," said Ninos Piro, 36, of Turlock, Calif. "They were trying to be a good influence on everyone around them. That's why you see everyone so torn up around here."
'Take a Wrong Step, You're Gone'
Joe Kolb of Fresno, Calif., said his family hiked the Mist Trail at least have a dozen times this year, and that hikers were taking a risk if they went near the water.
"The water running the way it is, if you take a wrong step, you're gone," Kolb said.
The presumed deaths of the three hikers Tuesday bring the number of Yosemite's water-related deaths to six. Olsen said the National Park Service urges visitors to observe the signs, online tips and brochures.
"For safety, the things you do at home, at school, at work, those things you do to keep yourself safe -- don't leave those things home when you go on vacation," Olson said. "Many people say safety involves a large dose of common sense. There is plenty of adventure in national parks by staying on the safe side of a handrail."
The Dangers of Nature
There have been other deaths recently in or around national parks or natural landmarks.
In April, Greg Seftick, 31, and his friend, Walker Kuhl, 27, disappeared while climbing and camping in Grand Teton National Park in Wyoming. They were both found buried under an avalanche.
Earlier this month, David Potts, 44, of California, was sucked into a blowhole and apparently killed during a vacation on Maui. Witnesses said he was dancing around before a wave knocked him down.
The blowhole had been featured in several travel websites, according to The Associated Press. Though Maui officials said the blowhole was on private property, the company said it was on public property because of rules regarding shoreline accessibility.
On Wednesday, Lindsay Burgess, 30, of Missouri, reunited with the boat captain who rescued her from the churning waters of Niagara Falls' Whirlpool State Park after she fell in while trying to touch the water.
Staying Safe With Nature
Before you head out into the wilderness, the National Park Service offered these safety tips:
Wear sturdy shoes and a hat.
Carry water and a flashlight.
Remember the sun and heat and poisonous snakes and plants.
Know your rock climbing and hiking limitations.
Leave an itinerary with family and friends and stick to it.
ABC News affiliate KFSN-TV and The Associated Press contributed to this story.