A 33-year-old man drowned last week while practicing face-down meditation on the Yuba River.

Yoav Timmer, a citizen of Israel, died at Rice's Crossing, northwest of Nevada City, around 3:30 p.m. on Friday, June 16, The Union reports. Timmer was practicing a type of meditation that involves floating face down in the water for a period of time. A friend meditating nearby checked on Timmer, according to the Sacramento Bee, and found him unresponsive.

Timmer's companion attempted life-saving measures and drove to the nearest home to call 911. Authorities pronounced Timmer dead after attempting to revive him, The Union says.

The death was the first in a series of drownings in Northern Californian rivers that have led officials to post several warnings about the dangers of the cold, swift waters resulting from melted snowpack runoff.

Two days after Timmer was found dead, authorities responded to another suspected drowning on the Yuba River, this time near the Hampshire Rocks campground on the South Yuba River.

Jairus Johnson-Neal, 21, was seen floating downstream of his friends on Sunday, June 18 according to a statement from the Placer County Sheriff's Office. His friends attempted to pull him from the river, but were unsuccessful due to the water conditions. Divers later recovered the 21-year-old's body 12 feet below the surface.

On Tuesday, Placer County officials once again reported a drowning in the region. According to KTLX, a 20-year-old swimming with friends succumbed to the cold temperatures and fast currents of the American River in Auburn. A search helicopter helped locate the body later that day.

Officials from Placer County urged swimmers to practice caution in the water in a Facebook post on Tuesday.

"PLEASE, stay out of the cold and rapid water in our local rivers," authorities wrote. "If you must enter the water, wear a life jacket. Summer officially began today, and many more weeks of cold, fast flows are predicted."

Read Michelle Robertson’s latest stories and send her news tips at mrobertson@sfchronicle.com.