Police in eastern England said Thursday a man had been arrested on suspicion of attempted murder after a 3-year-old boy "ended up in the crocodile enclosure" at a zoo. 

Cambridgeshire Constabulary said the toddler had sustained "serious injuries" and was in a "critical but stable" condition at Addenbrooke's Hospital in nearby Cambridge.

It did not specify how the injuries had been inflicted or whether they were from a crocodile. 

"A 30-year-old man from Norfolk has been arrested on suspicion of attempted murder," the police force added, noting specially trained officers were supporting the boy's family at the hospital.

It said detectives from its major crime unit were investigating the incident at Johnsons of Old Hurst, a zoo, farm shop and cafe around 20 miles northwest of Cambridge.

No further details about the incident were provided.

"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," Detective Inspector Verity McCann said in the police statement.

"We do not believe the man arrested and the child are known to each other."

Johnsons of Old Hurst is a family-run farming business that now features a butcher, farm shop, tea room and steakhouse as well as a zoo, according to its website.

It says it is home to more than 100 animals, including lions, tigers, sloth bears, capybaras, meerkats and crocodiles.