Severino was removed from Friday's game against the Yankees with right arm soreness, Martin Gallegos of MLB.com reports.
Severino gave up four unearned runs and struck out a batter during his lone inning of work before his arm forced him to leave his start prematurely. The A's will presumably send him in for imaging to determine whether a structural issue is causing his soreness, and more details on his injury could come out in the near future.