PAGE, Ariz. — A man is presumed drowned after disappearing while trying to rescue other swimmers on the San Juan River.

The National Park Service said Benjamin Saltwater, 23, of Kayenta, Ariz., disappeared on Tuesday while trying to help others who were having difficulty swimming the river in the Glen Canyon National Recreation area.

"He went under and did not resurface. It is unknown if he was wearing a life jacket," the National Park Service said in a statement Friday. "The other four swimmers were able to return to shore and summon help."

A search is under way for Saltwater's body.