Elias Lindholm also produced the first goal of his NHL career for the Hurricanes, who handed the Capitals their third loss in four games.
Gerbe's goal, his third of the season, came 6:59 into the final period and Anton Khubodin maintained the lead by stopping 30-of-32 shots.
Washington twice moved in front only to have Lindholm and Alexander Semin tie the contest with their second-period scores.
Braden Holtby allowed all the Carolina scoring on 36 shots.
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