A grandfather fatally shot his 18-year-old grandson in northwestern Waushara County during the opening weekend of Wisconsin's nine-day gun deer-hunting season, a warden says.

David R. Ruck from the Saxeville area died at a Neenah hospital after he was shot Sunday morning, Sheriff David R. Peterson said.

"My heart goes out to the family and to the community," said Tim Lawhern, conservation warden and state director of the Hunter Education Administration.

Deputies responded to a report about 8:40 a.m. that a hunter had been shot on private property in the town of Saxeville.

Ruck had been shot in the upper leg and inner groin, Peterson said, adding that the shooter said he mistook Ruck for a deer.

The sheriff's department and state Department of Natural Resources were investigating.

The gun deer season opened Saturday, with an estimated 630,000 hunters participating.

No statewide deer kill figures were reported Sunday.