Update 2:41 p.m.
Fairfield Police Chief Gary MacNamara said of the drowning, "Unfortunately we didn't have a successful conclusion. It's a tragedy."
Fairfield police identified the man as Frank Mazzabufi, 39, of Shelton.
They said he walked "a far distance from the swimming area" before jumping into a 20-foot deep area with unpredictable currents.
The lifeguards saw his distress and swam out quickly, but he had gone under by the time they reached him, police said.
"The area is unpredictable," MacNamara said. "It's a huge dropoff and a strong current."
He cautioned all swimmers to know their limits and obey posted swimming regulations. "We encourage people to swim in designated areas with lifeguards," the chief said.
It is the second drowning in Fairfield, he noted. A senior drowned at Penfield Beach earlier this summer.
MacNamara and Fairfield Assistant Fire Chief George Gomola, incident commander, praised the lifeguards and the beach director for a quick response.
The lifeguards "triangulated the exact position," making the search easier. Firefighters dropped an anchor about where they believed he went down and his body was found about 10 feet from the spot 20 feet down, Gomola said.
"Despite the negative outcome, all the agencies involved worked together," he said.
The lifeguards especially "did everything they could" under the leadership of their supervisor. "They could not have done anything more," Gomola said.
The assistant chief also noted that agencies worked together on a Hazardous Materials call earlier this week. "Our goal is to learn from each incident," Gomola said.
Update 1:29 p.m.
Police have pulled the body of a Shelton man in his 30s from Lake Mohegan.
The man, not yet identified by name, was discovered dead and taken from the water at 12:30 p.m. today.
Stay with Fairfield Patch for updates.
Police divers and firefighters from Fairfield, Trumbull, Westport and Bridgeport are scouring Lake Mohegan for a man who went underwater while swimming earlier today.
Several witnesses said the man was fishing with a female companion 300 feet north of the beach when he became disturbed, stripped down to his underwear and started swimming, Fairfield Police Lt. Jim Perez, department spokesman, said just after 12 p.m.
The man began screaming and flailing, and lifeguards responded immediately but were unsuccessful in retrieving him, police said.
Fairfield firefighters also responded.
He went under where the lake's depth reaches 30 feet, Perez said.
"We have all the resources we can possibly use. We are in rescue mode. We are very optimistic we will have a very successful rescue. We are determined to recover and save this individual," Perez said.
The lake is 25 acres and borders on GE World Headquarters. A command post has been set up, Perez said. Police are also searching around the lake to see if he came ashore anywhere.
The female companion told police the man may suffer from "flashbacks."
Before he ran into the water, the man asked her, "Am I OK? Am I OK?" Perez added.