Witnesses say Ramina Badal, Ninos Yacoub, and Hormiz David went over Vernal Fall and into the Merced River Tuesday.
So far, crews have only been able to walk the trail in search of the hikers, because the water flows are too treacherous.
The three were taking photos and playing in the water when they went over the waterfall.
A concert will be held in Stanislaus County Saturday night as part of a memorial for the three hikers. It starts at 7:30 p.m. at the Larsa Banquet Hall.
Larsa Banquet Hall
2107 East Monte Vista Avenue
Denair, California 95316.