A Detroit man died Sunday afternoon after he drowned in a lake in Keego Harbor, the Oakland County Sheriff’s Department said.

The 26-year-old, whose name hasn’t been released, was on a 20-foot boat with other people in Cass Lake, the department said in a press release.

The group had been trolling over a sandbar. The man entered the lake after the boat moved to a deep part of the lake, apparently unaware the boat no longer was over the sandbar, according to the sheriff’s office.

The man, who could not swim, lost contact with the boat. A friend jumped in to help him, but was only able to bring him to the surface momentarily because “the man was panicking and the friend could not hold him.”

Divers found the man approximately 1,700 feet from the shoreline, the sheriff’s office said. First responders administered CPR. The man was taken to a hospital and died there.

“With the onset of warmer weather and a substantial increase in water activity, we urge people to employ flotation devices and wear them if they are not strong swimmers, irrespective of the situation,” Oakland County Sheriff Michael Bouchard said. “Additionally, it is crucial to have life-saving equipment on board boats to rescue individuals in distress. An enjoyable day on the water can rapidly become a tragic moment.”

At least 11 people drowned in Oakland County’s inland lakes by early August last summer, up from four the year before. Officials called the spike in accidental drownings unusual and highlighted the importance of water safety awareness and having personal flotation devices on boats.