An Idaho man died during a rafting trip on the Colorado River in the Grand Canyon on Thursday.

The National Park Service said the 30-year-old man entered the river at the top of Hance Rapid, at Colorado River Mile Marker 77, with his rafting group.

Multiple rafting websites list Hance Rapid as one of the most complicated rapids on the Colorado River.

Information on what happened is unclear, but the national park said the man was pulled from the water by his group, unresponsive.

Grand Canyon National Park received an emergency alert from the river sometime later at 11:15 a.m.

Another notice was issued shortly after to say CPR was being performed.

Park rangers were flown into their location by park helicopter and also attempted CPR.

The national park said resuscitation efforts on the man weren’t successful.

An investigation into the man’s death is underway.