CONCORD (CBS) — The body of a missing swimmer was recovered from Walden Pond, officials said.

The regional dive team and Massachusetts State Police were called when a witness said they saw a 28-year-old man dive into the water and not come back up around 6:30 Sunday evening.

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The scene at Walden Pond after a missing swimmer is pulled from the water (WBZ-TV | Jim Smith)

Officials said the man was found after he was underwater for about an hour, taken by a boat to the shore, and then transported to Emerson Hospital. He was later pronounced dead.

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“I believe he was in 12 feet of water, the clarity of the water changes though because of the pollen in the water, so we can’t see the bottom,” said an official on the scene.

Lifeguards had already left for the day before the time of the drowning.

The man was found in a remote section of the pond known as Thoreau’s Cove.  Officials said it was unclear if a lifeguard would have been able to save him had one been on duty.

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The Middlesex District Attorney later released a statement that said, “this death is not considered suspicious no additional information will be released.”