Source: RB Donald Brown among 3 released by Patriots

— -- FOXBOROUGH, Mass. -- The New England Patriots released veteran running back Donald Brown on Tuesday, a source told ESPN NFL Insider Field Yates, as an early-camp injury ultimately doomed Brown's chances of sticking on the roster at a position where the club is thin.

Brown, who signed a one-year, $965,000 contract with the Patriots in March, was competing for a backup spot behind LeGarrette Blount and Dion Lewis, the latter of whom will open the season on the reserve/physically unable to perform list as he will undergo a second surgery on his left knee.

Brown had pulled up in the fifth practice of training camp -- members of the athletic training staff appeared to be checking his hamstring -- and hadn't been a full participant in practice since. He didn't play in the team's first two preseason games.

Brown entered the NFL as a first-round draft choice of the Indianapolis Colts, playing five years with them before spending the 2014 and 2015 seasons with the San Diego Chargers.

By releasing him, the Patriots thin their ranks at a position that was already short on depth. Blount is the top power option, while third-year man James White projects to step in for Lewis as the top "passing back" until his return. The team also has Brandon Bolden (5th year), Tyler Gaffney (3rd year), Joey Iosefa (2nd year) and undrafted rookie D.J. Foster at running back.

In addition to releasing Brown, the Patriots also informed defensive tackle Frank Kearse and cornerback E.J. Biggers of their releases, sources told ESPN. Both were long shots to make the roster.