Per ESPN's Adam Schefter, Pumphrey tore his hamstring during an Eagles practice.
Per Jeff McLane of the Philadelphia Inquirer, Eagles head coach Doug Pederson said Pumphrey's injury is "significant" and the team "will have to decide on how to proceed."
Pumphrey had a successful four-year run at San Diego State, setting the FBS record for career rushing yards with 6,405. He also finished tied for 10th in 2016 Heisman Trophy voting after running for 2,133 yards and 17 touchdowns.
Philadelphia isn't lacking depth in the backfield. LeGarrette Blount is the primary running back, with Darren Sproles serving as a change of pace and Wendell Smallwood occasionally spelling both of them.