The coroner in Sauk County, Wis., says the preliminary cause of death of a toddler at a campground Saturday (July 17) is heat exposure, and police are seeking public assistance in investigating the incident.

Sauk Prairie Police Chief Jerry Strunz said authorities are in the process of interviewing people who were at the VFW Campground in Prairie du Sac when the boy, identified Monday as 16-month-old Tanner Lee Nelson of Mauston, was found unresponsive, the Sauk Prairie Eagle reported.

The campground was filled with those who attended the weekend’s Freedom Ride, an annual charity motorcycle ride that benefits the Muscular Dystrophy Association of Wisconsin.

“The MDA ride brings in a large crowd from a large area and many from out of state, so we’re trying to talk to as many of those people as possible,” Strunz said in a phone interview Monday, adding that the incident occurred on the north end of the park in what he referred to as the “overflow camping area.”

Strunz stated in a news release that someone notified first responders of an unresponsive child at the campground around 2:39 p.m. Saturday. Sauk Prairie EMS arrived at 2:43 p.m. and took over life-saving efforts from a female who was performing CPR on Tanner, the release said.

Kevin Sarto, director of the Sauk Prairie Ambulance Service, said he’d heard it was the boy’s mother who called 911, but he wasn’t certain. He declined to discuss Tanner’s condition when EMS arrived at the scene, but despite the temperature climbing to the high 80s, he said it was the only heat-related call the service responded to Saturday.

Ambulance workers transported Tanner to Sauk Prairie Memorial Hospital where he was pronounced dead at 3:18 p.m.

Coroner Betty Hinze said Monday the boy was asleep in the family’s trailer when it was very warm. Hinze said the trailer had an air conditioning unit, but police are investigating whether it malfunctioned.

More than 1,400 bikers were in Sauk Prairie for the Freedom Ride, said Crystal Mundt, general manager for Sauk Prairie Harley Davidson, which hosts the event. Mundt said the Harley dealership managed the campground over the weekend because it’s the official camping spot for the two-day event.

“What happened was a horrible accident,” Mundt said, adding that it had nothing to do with the Freedom Ride. She said she wouldn’t comment on what happened to the boy because she wasn’t there.

Strunz said he is withholding certain details about the incident at the request of the Sauk County District Attorney’s Office because it is important that witnesses who might come forward not be tainted by anything they might have heard or read about the boy’s death.