A Sacramento, California teen is missing after being swept over a waterfall at Yosemite National Park.

According to the U.S. National Park Service, 19-year-old Aleh Kalman was swimming above Nevada Fall (pictured) on Saturday after noon. At around 2:45, Kalman was swimming to shore from a rock in the middle of the river when a current swept him over the edge of the waterfall. Kalman had come to Yosemite with a church group and was hiking the Mist Trail.

Park authorities and the California Highway Patrol (CHP) organized a search effort for Kalman that included dog teams and a CHP helicopter. Search efforts continued until Saturday night and resumed on Sunday, but the teen’s body has not been found. A large section of the Mist Trail is closed while the search continues.

Nevada Fall is a 594-foot fall located on the Merced River. The National Park Service has warned park visitors that rivers in Yosemite run at high levels this time of year, and are extremely cold.

The incident comes less than one month after the body of another hiker was found near the bottom of Vernal Fall, a 317-foot waterfall also located in Yosemite. The 73-year-old man reportedly fell from a cliff near the top of the fall.

(Photo by DAVID ILIFF. License: CC-BY-SA 3.0)

[CORRECTION:] Nevada Fall is 594-feet high, not 150-feet.