DELAWARE, Ohio (AP) _ A driver was hospitalized after a four-horse pileup during Monday's sixth harness race at the Delaware County Fairgrounds.

Drivers Don Pfister and Jeff Nisonger were taken to Grady Memorial Hospital. Hospital spokeswoman Terry Morgan said Nisonger was treated and released, but Pfister was receiving treatment. She would not provide Pfister's condition or the nature of his injuries.

The other drivers involved, Dale Edwards and Jim Dailey, walked away with minor injuries.

The accident took place when Pfister's horse, Victor Bloom, tripped and fell down and R W's Outa Towner, driven by Nisonger, flipped over him. Max's Memory (Edwards) and Presidential Pride (Dailey) piled into the downed horses.

All four horses went down, but none appeared to be seriously injured.

The half-mile track hosts standardbred races all week leading up to Thursday's Little Brown Jug, the third leg of pacing's triple crown for 3-year-olds.