The neighbor, who wished to remain anonymous, said one of Harrison's three pit bulls attacked the football player's son, James Harrison III, at Harrison's home in Franklin, Pa., the Pittsburgh Post-Gazette said Friday.
Harrison, NFL defensive player of the year last season, promptly returned home after learning of Thursday's dog attack, the neighbor added. No age was given for Harrison's child.
Harrison's son was reportedly taken to Children's Hospital with unspecified injuries, but the hospital has refused to confirm James Harrison III is a patient there, the Post-Gazette said.
The newspaper said another individual, thought to be another of Harrison's family members, may also have been injured after the pit bull got loose Thursday.
A spokesman for the Steelers organization has tabbed the incident a personal matter for Harrison, who helped the NFL franchise win last season's Super Bowl.
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