A Jackson man drowned in the Green River last week, authorities reported.

David H. Ptak, 27, died July 28 after having a seizure while standing in the river, said Shane Templar, detective with Sublette County Sheriff’s Office.

Just after 9 a.m., Ptak and a friend unloaded a boat into the river.

While the friend went to park the vehicle, Ptak was holding onto the boat in knee-deep water.

While Ptak was standing in the water, he suffered a seizure that knocked him into the river and cause him to drown, Templar said.

Ptak had lived Jackson, Sublette County and Laramie, Templar said. He also lived in California.