A three-year-old boy critically injured in a zoo enclosure was attacked by a crocodile, the BBC understands.
Cambridgeshire Police said a 30-year-old man arrested on suspicion of attempted murder had been bailed and was "unfit for interview". He reportedly has learning difficulties and had been on a trip to Johnsons of Old Hurst, near Huntingdon, with carers.
It is believed the boy was attacked on Thursday by at least one crocodile after ending up in their enclosure.
He remained in a critical but stable condition. Police said the boy, who was from Cambridgeshire and visiting with his family, sustained serious injuries "while in the enclosure" and was pulled out by zoo staff.
He received medical treatment at the scene before being taken to Addenbrooke's Hospital in Cambridge.
Officers said they were called to the zoo at 13:34 BST on Thursday and were working to establish how long the boy was in the enclosure.
Police said the crocodiles had not been seized or killed.
Det Insp Verity McCann said: "Our inquiries are ongoing as we continue to understand the circumstances surrounding this distressing incident.
"Our thoughts remain with the boy, and his family and specialist officers continue to support them through this difficult time."
The man who was arrested was from Norfolk, police said, and was not at the zoo as part of an organised group visit.
People may be considered not fit to be interviewed because of their physical or mental state.
A witness told the BBC she had seen a man, accompanied by two women wearing lanyards who she believed may have been carers, walking through the zoo about 10 minutes before the incident.
She said they crossed paths as she and her daughter were entering the capybara enclosure and the group was coming out on to the forest walk.
The witness said she overheard one of the carers ask: "Should we go to the crocodile house next?". The man replied: "Yeah."
A spokesperson for Johnsons said on Thursday their thoughts and prayers were with the boy and his family.
They added that the site's Tropical House, which contains the crocodile enclosure, had been closed "out of respect to the family".
Zoo staff were seen arriving at the site earlier on Friday and it opened as normal apart from the Tropical House.
Crocodilians first arrived on the family-run farm in 2006 and species now include broad snouted caiman, Nile crocodiles and American alligator.
They are kept in a converted cattle barn, which has metal-fenced elevated walkways looking down on large pools of water surrounded by tropical vegetation.
To celebrate the 20th anniversary of the first farm shop, a new museum at the site was due to open with a special weekend event starting on Saturday. It is unclear if the opening will go ahead.
One visitor, who wished to remain anonymous, told the BBC that she "didn't see the incident itself but heard the screams" and added that she later saw staff and an air ambulance responding at the scene.
Another visitor, who left about 10 minutes before the incident, said the crocodiles appeared calm and largely motionless during her visit.
The enclosure included "quite high fences" and they said there was "steel mesh fencing" all around the viewing platform.
A spokesperson from Huntingdonshire District Council, which is responsible for licensing such facilities, said Johnsons was "fully licensed".
"Its licence was renewed in 2024 following the statutory inspection and approval process. Public safety is a fundamental consideration in the licensing regime, including the suitability of animal enclosures and visitor barriers," they said.
The council added it was "not aware of any previous reportable accidents or incidents involving the crocodile enclosure" and that "no other safety-related incidents have been recorded through the zoo licensing process".
It said its environmental health team was in touch with the zoo managers and would "consider whether any further inspection or follow-up action is required".
Chris Newman, director of the National Centre For Reptile Welfare, told the BBC: "It's a reactatory animal. So, if something splashes next to it, surprises it, something jumps, his natural reaction is to turn and bite, and it would just be an investigative bite. They would quite often bite and let go."
He said Tracey Johnson, from the zoo, had shown "remarkable bravery" in entering the enclosure during the incident and pulling the boy out.
"I know Tracey very well and she's a lovely lady and it's nothing more than I'd expect from her," he said.
"She'd always put her own life at risk to save someone else. She's an extraordinary lady and very brave."
He said he had been told Johnson was not injured.
"She put herself in immense danger... I'm not sure if she was up and jumped in or if she was downstairs doing something with the animals when this happened."
On Thursday, police said they were speaking to people who were at the zoo at the time of the incident.
"We do not believe the man arrested and the child are known to each other," a force spokesperson said.
They added that CCTV from the venue was being reviewed by officers.
Huntingdon MP Ben Obese-Jecty urged people to "refrain from speculation online" and said police were treating it as a "critical incident".
A Magpas Air Ambulance spokesperson said a critical care team attended the incident at 13:42 BST on Thursday and "treated one patient at the scene before taking them to hospital".
According to its website, Johnsons of Old Hurst is a farming business that also features a butchers, a farm shop, tea room, steakhouse and zoo.
It says it "houses over 100 fascinating animals" including crocodiles, African lions and a Bengal tiger.
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