The Ravens organization say they have made contact with Pierce and are "aware of the situation.”
Pierce rushed 108 times for 532 yards and one touchdown in his rookie campaign, after being drafted out of Temple in the third round of the 2012 NFL Draft.
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Pierce and a male companion, sources say, were shaken but were not injured during the robbery. Sources say a gunman jumped from a car while his accomplice remained behind the wheel and robbed Pierce and his companion, then stole the vehicle. The car was recovered in another part of the city and taken to the police garage, where it was carefully processed for any possible evidence that might lead to a suspect.