(CNN) Three visitors were injured, one fatally, in falls in Yosemite National Park last week, and officials are imploring tourists to avoid venturing off-trail.

A 21-year-old man died after he slipped and fell from the base of a waterfall in the California park, National Park Service officials told CNN on Monday.

He was one of three people to slip near waterfalls in the park last week, officials said in a Facebook post

In two incidents July 29 and Wednesday, another visitor and the man fell 20 feet after slipping on wet boulders near the base of Bridalveil Fall, officials said. Both had left the marked trail to scramble up the sides of the boulders.

Rescuers clad in climbing shoes with sticky rubber soles scrambled up the slippery boulders to reach the visitors and provide life support, officials said. Both visitors were flown to the park's El Capitan Meadow, where ambulances met them.

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