Editor's note: This update identifies the missing individuals and provides additional details on how they entered the river.

Yosemite National Park officials were presuming Wednesday that three visitors who were swept over Vernal Fall were killed in the incident, though a search continued for their remains.

The three were identified as Hormiz David, 22, of Modesto, California; Ninos Yacoub, 27, of Turlock, California,; and Ramina Badal, 21, also of Modesto. The three had come to the park for a day trip with a group of family and friends. 

According to a park release, the two men and their female companion were seen entering the water above Vernal Fall, approximately 25 feet from the precipice.

"Witnesses reported to park officials that several people urged the group members to step back from the river, since it was flowing swiftly and extremely cold," the release said. "The area is signed as a dangerous area, and the group had crossed a metal guardrail placed there to keep visitors away from the dangerous fast-moving water."

Runoff in Yosemite this summer has been higher than usual due to a greater-than-normal snowpack. That makes for spectacular waterfalls, but also creates more dangerous conditions for visitors who stray too near streams.

The Mist Trail is among the most popular in the Yosemite Valley, leading up from the Happy Isles area past Vernal Fall and up to the brink of the Nevada Fall, where it connects with other trails leading to Half Dome and into the Little Yosemite Valley.

From Happy Isles to Nevada Fall the trail climbs about 2,000 feet on a trail that in places follows rock steps and steel ladders. Along the way it parallels the Merced River, and in places hikers can walk over to pools formed by the river as well as precipitous ledges the river catapults off.

Each day in summer about 1,500 people hike the trail, at least to the top of Vernal Fall, according to park officials. While the Park Service has placed guardrails in spots to keep hikers from getting too near the river and its falls, many people climb over or around them.

There have been six water-related deaths in Yosemite this year, including this incident, park officials reported. Two hikers drowned in the Hetch Hetchy Reservoir on June 29, and a hiker slipped and fell into the Merced River on the Mist Trail on May 13.

The Mist Trail had been closed since the incident to facilitate search and rescue operations, though it was reopened later Wednesday. Rangers were continuing search efforts throughout the day, primarily by combing each side of the Merced River looking for the
victims.

The park's search-and-rescue history is rife with incidents involving waterfalls. Charles "Butch" Farabee, Jr., a former park ranger, noted that in Off the Wall: Death in Yosemite, which he wrote with Michael Ghiglieri.

...it is immediately above the Valley's profligate array of gigantic waterfalls that all too many of Nature's lovers have communed too closely. Even today these scenic wonders still seem deceptive in size. So much so that some visitors who make the arduous effort to hike to the tops of these falls arrive there only to fail to comprehend their power. A few of their tragic stories defy belief. Unfortunately, all too many are real.