An Auburn teenager's medical condition improved overnight after he was involved in a tractor accident in the Town of Skaneateles Wednesday afternoon, Onondaga County sheriff's deputies said.

A spokeswoman for University Hospital said John Rice, 16, of Auburn, had improved from critical to good condition. Good is the best medical condition a patient can be listed in, while critical is the worst.

Deputies said the accident happened just after Rice picked up a load of stone with a bucket on the front of the tractor at 2:45 p.m. at the Cargile Farm at 3905 Gully Road. When Rice attempted to drive the vehicle up a hill, it began to roll backward, causing him to lose control.

The vehicle then tipped over when the front of the tractor went into the air and rolled over the back end, deputies said. Rice was ejected, but not run over, during the tractor's back-flip.

Rice suffered severe injuries as a result of the accident and was transported to University Hospital by helicopter, deputies said.

Deputies said an investigation was being conducted to determine why the tractor rolled down the hill.