Sidney Thornton, a two-time Super Bowl champion running back who played his entire career with the Pittsburgh Steelers, has died, the team announced Wednesday. He was 68 years old.

Thornton’s cause of death was not announced.

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Pittsburgh Steelers running back Sidney Thornton, #38, runs with the ball against Philadelphia Eagles defensive lineman Carl Hairston, #78, as offensive lineman Steve Courson, #77, blocks during a preseason game at Veterans Stadium The 15th of August. , 1981 in Philadelphia.
(George Gojkovich/Getty Images)

«We are saddened by the loss of former Steelers running back Sidney Thornton,» the Steelers said in a tweet.

Thornton starred at Northwestern State, where he set career records for rushing attempts (537), rushing touchdowns (25), and rushing yards (2,662) when he turned pro. Those marks have since been broken. Pittsburgh would take Thornton in the second round of the 1977 NFL Draft with the 48th pick.

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Sidney Thornton, #38 of the Pittsburgh Steelers, carries the ball against the Houston Oilers during an NFL game on September 7, 1980 at Three Rivers Stadium in Pittsburgh.

Sidney Thornton, #38 of the Pittsburgh Steelers, carries the ball against the Houston Oilers during an NFL game on September 7, 1980 at Three Rivers Stadium in Pittsburgh.
(Focus on Sport/Getty Images)

Thornton played six seasons with the Steelers from 1976 to 1982.

He played in 74 games for the Steelers and had 1,512 rushing yards and 18 rushing touchdowns. He also had 46 catches for 515 yards and six touchdowns. He appeared in the playoffs three times with the Steelers and was part of their Super Bowl-winning teams in 1978 and 1979.

Thornton was a backup behind Franco Harris and Rocky Bleier on those teams. He had a great game against the Miami Dolphins in the divisional round of the 1979 playoffs. He rushed for 52 yards and a touchdown in the 34-14 victory. Pittsburgh would hoist the Vince Lombardi Trophy that year.

Sidney Thornton, #38 of the Pittsburgh Steelers, carries the ball against the Cleveland Browns during an NFL game on October 15, 1978 at Cleveland Municipal Stadium in Cleveland.

Sidney Thornton, #38 of the Pittsburgh Steelers, carries the ball against the Cleveland Browns during an NFL game on October 15, 1978 at Cleveland Municipal Stadium in Cleveland.
(Focus on Sport/Getty Images)

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He took two years off from soccer before playing a season in the United States Soccer League with the Oklahoma Outlaws.