A woman has been killed in an apparent shark attack while swimming off the coast of Maine, New England, police have said.
She was spotted by witnesses in the water off Bailey Island in the Casco Bay on Monday before being injured by what they believe was a shark.
Cumberland Cty Sheriff Ennis Wright said the incident "appears to be a shark attack" off of Harpswell, a collection of islands and peninsulas northeast of Portland.
The northeasternmost US state has never before recorded a fatal shark attack in its history.
The Coast Guard has confirmed it was called to the incident at 3.30pm near White Sails Lane.
Quick-thinking kayakers frantically pulled the injured woman from the water and took her back to shore before paramedics pronounced her dead at the scene.
The woman has not yet been identified, with her next of kin to be notified.
Authorities say she was swimming with someone else when it happened.
Boater Stacey Guth said she had never heard a distress call like it when it came in over the radio on Monday afternoon, reports Bangor Daily News.
"We have never heard a ‘mayday’ over our radio in all of our hours out on the water, but heard today a ‘pan-pan’ which means urgent, but not yet vessel or life-threatening," said Ms Guth, of Portland, who was nearby aboard the vessel Stinkpot.
"It was for a possible shark attack not far from where we were."
The Marine Patrol has warned boaters and swimmers from entering the water until further notice.
The only other recorded unprovoked attack in Maine was in 2010 when diver Scott MacNichol used an underwater camera to fight off an estimated eight-foot, 300-pound porbeagle as it moved in on him.
