Westport police say a coordinated rescue effort in the Long Island Sound was successful even though authorities are confident no one was actually in the water.

The Westport Police Department teamed up Sunday with Connecticut state police, the Coast Guard, various fire departments and officers from Norwalk and Fairfield to frantically comb the estuary after a witness told police a swimmer had gone missing.

Authorities used boats, all-terrain vehicles, a helicopter and divers during the rescue effort. After several hours, they felt confident enough to call off the search.

"At [that] point we have to make the assumption that there was a swimmer, and we're hoping he made it back," says Sgt. Jerry Shannon, of the Westport Police Department.

Shannon estimates that thousands of dollars in departmental resources were utilized in the effort. Police say they're still willing to talk with people who may have seen something suspicious in the water Sunday near Compo Beach.

They're asking anyone with information to call 203-354-INFO.

Crews call off search for missing swimmer in Westport Witnesssays swimmer drowned in Long Island Sound