The Coast Guard searched the waters off Truro, Massachusetts on Saturday for a 26-year-old man, but suspended those efforts by nightfall pending further developments.
State and local agencies plan to resume Sunday morning.
Authorities were notified of a person in the water near Ballston Beach at 2:30 p.m., according to a Coast Guard statement. A response boat crew from the Provincetown Coast Guard station and an air crew from the Cape Cod Air Station responded.
A Massachusetts State Police helicopter, the Truro Police Department, and a dive team from the Sandwich Fire Department also assisted.
Anyone with additional information is asked to contact Sector Southeastern New England, at (508) 457-3211.