Charles Johnson, a star wide receiver at Colorado and first-round draft pick of the Pittsburgh Steelers, has died at 50.

The cause of Johnson's death was unknown as of Wednesday afternoon. He had been working as the assistant athletic director at Heritage High School in Wake Forest, North Carolina, at the time of his death, which was confirmed by Colorado.

Johnson was selected by the Steelers with the 17th overall pick in the 1994 NFL draft and played five seasons for Pittsburgh, hauling in 247 receptions for 3,400 yards and 15 touchdowns. His best season with the Steelers was in 1996, when he had 60 catches for a career-high 1,008 yards and three touchdowns.

Johnson also spent two seasons with the Eagles, one season with the Patriots and one with the Bills. He was a member of New England's Super Bowl-winning team in 2001.

Johnson played four seasons at Colorado and was a standout over his final two years. He had 1,149 receiving yards and five TD catches as a junior before finishing with 1,082 receiving yards and nine TD catches as a senior in 1993.