A man has been arrested on suspicion of attempted murder after a three-year-old boy was left with critical injuries after ending up in a zoo's crocodile enclosure.
Cambridgeshire Police said it was called to Johnsons of Old Hurst, near Huntingdon, at 13:24 BST.
A villager, who did not want to be named, told the Press Association the zoo owner's wife jumped in to try to save the boy.
A 30-year-old man from Norfolk has been arrested on suspicion of attempted murder and officers added that they do not believe the man and child were known to each other.
The force said it was investigating whether the child was attacked by the animals.
The boy was taken to Addenbrooke's Hospital with serious injuries and is in a critical but stable condition, the force said.
A spokesperson for Johnsons of Old Hurst said its thoughts and prayers were with the boy and his family.
"Out of respect to the family, our Tropical House will remain closed until further notice," they added.
"If you have any questions about the incident, please direct inquiries to Cambridgeshire Police Constabulary.
"The rest of the site will remain open as normal."
Det Insp Verity McCann, from Cambridgeshire Police, said: "At this stage we are speaking to people who were at the zoo at the time of this distressing incident to understand more about the circumstances.
"We do not believe the man arrested and the child are known to each other. Officers are supporting the boy's family at hospital, and our thoughts remain with them."
Huntingdon MP Ben Obese-Jecty wrote on social media that his "thoughts were with the young victim and his family during a hugely traumatic and difficult time" and he urged people to "refrain from speculation online".
He said he was "liaising with senior officers at Gold Command who are treating this as a critical incident".
Darryl Preston, Cambridgeshire and Peterborough's police and crime commissioner, said he had been briefed by Chief Constable Simon Megicks.
"My thoughts go out to the family of the little boy involved in this truly horrific incident," he said.
"I can only begin to imagine the trauma those involved are going through."
A spokesperson for the East of England Ambulance Service said an ambulance, a rapid response vehicle, an ambulance officer vehicle and Magpas Air Ambulance attended the scene.
"A child was transported by road to hospital for further care," they added.
A Magpas Air Ambulance spokesperson said a critical care team attended the incident at 13:42 and "treated one patient at the scene before taking them to hospital".
A near neighbour of the zoo, who did not wish to be named, described hearing a "lot of sirens" then an air ambulance arriving.
He said the incident was "shocking".
Mike Annicelli, 52, who also lives close to the zoo, said he had previously visited the attraction.
He said there was a "raised platform" in the enclosure and estimated the crocodiles were about 15ft (4.5m) below. He said there was fencing along walkways which he estimated was around 4ft (1.2m) high.
According to its website, Johnsons of Old Hurst is a family-run farming business that now 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.
The crocodiles are kept in a converted cattle barn, which has metal-fenced elevated walkways looking down on large pools of water surrounded by tropical vegetation.
Charlotte Lowe, who represents Old Hurst on Huntingdonshire District Council and Cambridgeshire County Council, said she was "shocked" when she heard about the incident.
"To have something like this happen here is just incredulous," she said. "You don't expect this to happen in a rural village."
The enclosure had safety measures in place, she added, including Perspex glass and secure walkways, and the zoo was a popular attraction to visitors from all over the country.
"Our thoughts and prayers are with the family of the young boy suffering in this," she added.
