Manhattan ? Authorities in Kansas say an unexplained internal injury caused the death of a Nebraska man attending the Country Stampede musical festival.

KJCK-AM said Pottawatomie County Sheriff Greg Riat reported Friday on the autopsy on 19-year-old Jacob Kruetzer of Beaver Crossing, Neb.

The sheriff said Kruetzer was found unresponsive at a campground at Tuttle Creek State Park and died early Thursday while being rushed to a hospital in Manhattan.

Riat says Kruetzer talked to family members around 8 p.m. Wednesday. He was checked by security at the campground about 2:30 a.m. Thursday and again about 15 minutes later, when he was taken to the hospital.