A four-metre alligator has been killed, after it was spotted in a Florida canal with the remains of a woman’s body in its mouth.

Authorities were alerted to the grisly sight in Largo, in the Tampa Bay area, on Friday afternoon.

Jamarcus Bullard said he was walking to a job interview when he spotted the gator carrying what he initially thought was a mannequin.

“I noticed it had a body in its mouth – like a lower torso. So once I saw that I ran straight to the fire department,” he told local broadcaster Fox 13.

“It was my first time seeing a gator in real life. So I was like it’s pretty cool, but once I saw what it had I was like ‘is that like a mannequin?’

“It was pale and white.”

“It was just clamped onto it, and swam backwards to the bottom of the canal. .. I just couldn’t believe it was real,” Bullard said in another interview with 10 Tampa Bay.

He said he also started videoing the animal.

News footage shows a huge alligator sprawled beside a road surrounded by police and emergency vehicles.

The Pinellas County Sheriff’s Office said later the animal had been euthanised. The victim, whose remains were found by a police dive team in the canal, was identified as 41-year-old Sabrina Peckham.

A fundraising page has been set up for Peckham by her family. They said she was living in a homeless camp in the area at the time of her death.

“It is believed that she may have been walking to or from her campsite near the creek in the dark and the alligator attacked from the water,” Breauna Dorris, who said she was Peckham’s daughter, wrote on Facebook.

“No one deserves to die like this.”

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Alligators have been spotted in the area before. But resident Jennifer Dean told Spectrum News 13 that she had never seen as big.

“It’s crazy. My kids walk by there all the time. So it’s really scary. I’ve seen four or five-feet gators but nothing that big,” she said.

“A lot of my neighbours were out here and they’re the ones that told me about the gator. While we were standing here we heard a shot. I assume they killed the gator.”

Bullard said: “I’m going to get me a bike or start catching the bus to work. They have small little gates, but somebody died.”

-with agencies