Country music superstars Tim McGraw, 33, and Kenny Chesney, 32, were arrested late Saturday night in upstate New York after Chesney allegedly hijacked a policeman's horse and McGraw attacked deputies who tried to corral Chesney. The two singers were in Buffalo, N.Y., as headline performers of the George Strait Country Music Festival. The melee reputedly began in a parking lot when Chesney asked the daughter of a police captain if he could briefly mount her father's horse. She said yes. McGraw, who was named father of the year on Friday by the National Fatherhood Initiative (and is married to country star Faith Hill), was slapped with a felony charge of assaulting a police officer, as well as misdemeanor charges of obstructing governmental administration, resisting arrest and menacing. He was released on $2,500 bail. Chesney was charged with disorderly conduct and released on $100 bail.