A three-year-old boy is in a critical condition after being injured in a crocodile enclosure at a popular British zoo west of London. In a statement, Cambridgeshire Police said they had arrested a 30-year-old man on suspicion of attempted murder following the incident. They were called to Johnson's of Old Hurst, otherwise known as Johnson's Zoo, shortly after 1pm local time on Thursday (10pm AEST), after reports that the boy had ended up in the attraction's crocodile enclosure.