LONDON — A toddler was in critical condition Friday after being injured by a crocodile inside of an enclosure at a United Kingdom zoo, British police said.

The three-year-old boy, who has not been named, was pulled out of the crocodile enclosure Thursday at Johnsons of Old Hurst Zoo in Cambridgeshire, in southern England, by staff, and rushed to a local hospital.

Police did not say how the child ended up in the reptile’s enclosure, but they said a 30-year-old man was arrested on suspicion of attempted murder.

“The man, who is not known to the victim, was assessed as not being fit for interview,” Cambridgeshire police said in a statement.

The unnamed man was released on bail Friday while detectives continue their investigation, the statement added.

The child “sustained serious injuries while in the enclosure,” police said, and remained “in a critical but stable condition.”

“Our thoughts remain with the boy, and his family and specialist officers continue to support them through this difficult time,” Detective Inspector Verity McCann said. “Our enquiries are ongoing as we continue to understand the circumstances surrounding this distressing incident.”

The family-run zoo said in a statement that its Tropical House, where the crocodiles were kept, would be closed until further notice, “out of respect to the family.”

The zoo houses over one hundred animals including lions, tigers and capybaras, according to its website. Its staff have maintained “a particular fascination with crocodiles. We have cared for and been involved with these incredible animals for the past two decades.”

Adela Suliman is a breaking-news editor and reporter for NBC News in London. She covers news as it unfolds in the United States and around the globe. Previously, she has worked for The Washington Post, Al Jazeera English, Reuters and The Associated Press. She is a graduate of the School of Oriental and African Studies (SOAS), University of London, with a degree in Law, and Columbia’s Graduate School of Journalism. Before pivoting to journalism, she worked as an international corporate litigator in London, Dubai and Libya. She grew up in Manchester and London but also spent long stints in Khartoum, the Sudanese capital, where her father was born.