Mercer Island police say a man died Sunday afternoon while paddleboarding in Lake Washington off Luther Burbank Park.

Police Cmdr. Jeff Magnan said the man, believed to be 47 years old, was in the water for more than an hour while police and fire officials from Mercer Island and Renton Fire Department searched for him.

He was found shortly before 6 p.m. about 30 yards off shore between the dock and the swim area of the park’s beach. Efforts by medics to revive him were unsuccessful, Magnan said. An autopsy by the King County Medical Examiner will determine the cause of death, he said. His identity was not released pending notification of next of kin.