Two people drowned in separate incidents along the Russian River Sunday, prompting renewed safety warnings amid a troubling pattern of summertime deaths on the popular Sonoma County waterway.

The first drowning victim, a juvenile, was found underwater after a 20-minute search at Monte Rio Beach during an afternoon rescue attempt that included a second juvenile, the Sonoma County Sheriff's Office said. One of the juveniles was rescued, but the second was declared dead at the scene after attempts at CPR.

A San Francisco man and Oakland boy drowned in two separate incidents in the Russian River last weekend, authorities said.