A 22-year-old visitor to Yosemite National Park died Saturday after being swept over the 594-foot Nevada Fall, officials confirmed this week. The victim was identified by local authorities as Josue Baires Alfaro, according to reports.

Freesia Gaul, a fellow parkgoer who witnessed the incident, told SFGate that she was taking a photo when she spotted Alfaro in the Merced River. Gaul, a former volunteer lifeguard, said Alfaro did not appear to be a “strong swimmer.” She jumped into the water to try to save him.

“People see calm water, but they don’t realize that under that there’s a huge undercurrent,” Gaul told SFGate. “When you see someone like that, when you make direct eye contact with someone who you know is going to go over, you can’t turn around.”

Gaul said she could not reach Alfaro in the turbulent current and struggled to stay afloat herself. She told SFGate she believed her survival odds were bleak until a bystander extended a walking stick into the water. Gaul grabbed it and avoided being swept over Nevada Fall.

The National Park Service has opened an investigation into Alfaro’s death, the Los Angeles Times reported.

Yosemite, located about three and a half hours east of San Francisco, is one of the most visited national parks in the United States, attracting approximately 4 million visitors annually.

The park has seen multiple deadly incidents at or near Nevada Fall in recent years. In 2013, a 19-year-old from California died after swimming in the Merced River and being swept downstream to the waterfall’s edge. In 2018, an Israeli teenager died after falling 800 feet down a cliff while taking a selfie near the same waterfall.

The National Park Service has advised visitors to use “extreme caution” near any flowing water or wet rock in the area.