Police said they got the call at around 9:30 Sunday morning, and responded with members of the National Park Service.
As the authorities arrived, one of the swimmers was making it to the shore, but another was still trapped in a swirling mix of strong currents and rough waves.
Eastham Police credited Officers Jake McGrath and Vicki Wagner, along with an unnamed National Park Service Ranger, with pulling the man from the water.
The Eastham Fire Department evaluated the man when he got to shore. Eastham Police said the incident "could have had a tragic outcome" if not for the officers.
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