(CNN) A California woman died after she lost her footing and was swept over a waterfall at Lake Tahoe, authorities said.

Dina Espinosa, 35, of the San Francisco Bay area, was sitting in a natural pool Friday when she slipped while reaching for a branch, the El Dorado County Sheriff's Office said in a release. She was "swept away in the very fast moving waters over the waterfall," the release said.

"Don't underestimate the power of waterfalls, rivers, and cold water temperatures," the North Tahoe Fire Protection District said on its Facebook post about the incident.

Espinosa's brother, Nick Martinez, told CNN affiliate KOVR that his sister wasn't taking photographs and didn't have her phone on her when she fell.

The North Tahoe Fire Protection District in its post had urged caution when "taking selfies and other photos in dangerous areas," and media outlets reported that Espinosa had been taking photos.

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