Former NFL running back Marion Barber III has died, the Dallas Cowboys said in a statement Wednesday. Barber, who fans affectionately knew by the nickname “Marion the Barbarian,” was 38 years old, KTLA sister station KETK reports.

Officers found Barber dead in his apartment on Wednesday, the Frisco Police Department told the Fort Worth Star-Telegram. Barber was unresponsive when police arrived, KXAS reports, but the cause of his death was unknown, as of this writing.

A Frisco police spokesperson told Fort Worth Star-Telegram that officers found Barber after responding to “a welfare concern,” but declined to add additional details pending a full investigation by police and the Collin County Medical Examiner.

Barber, whose birthday would have been on June 10, played seven years for the NFL. For six out of the seven years, he played for the Cowboys, between 2005 and 2010. Barber also played for the Bears, finishing his career in Chicago in 2011.

The Dallas Cowboys released the following statement:

“We are heartbroken by the tragic death of Marion Barber III. Marion was an old-school, hard-nosed football player who ran with the will to win every down. He had a passion for the game and love for his coaches and teammates. Our hearts go out to Marion’s family and friends during this difficulty time.”

Throughout his career in the NFL, Barber rushed 4,780 yards, on 1,156 attempts, an average of 4.1 yards per attempt, and scored 53 touchdowns on the ground. As a receiver, he caught 179 passes for 1,330 yards with six TDs.

According to KXAS, Barber was known for his humanitarian efforts and for giving back to his community.