A woman has been arrested on suspicion of neglect after a five-month-old boy suffered a cardiac arrest at Legoland Windsor Resort.
The baby is in critical condition in hospital after the incident at about 1pm on Thursday, police said.
A 27-year-old woman from Witham, Essex was arrested on Friday on suspicion of neglecting a child to cause unnecessary injury. She has been released on police bail until 26 July.
DC Zoe Eele, of the Thames Valley police’s child abuse investigation unit, said: “We are investigating a distressing incident involving a very young child at Legoland Windsor earlier this week.
“Firstly, our thoughts are with the family of the boy who is in a critical condition in hospital after suffering a cardiac arrest. We are supporting them as best we can at this extremely difficult time.
“We are working closely with the team at Legoland Windsor Resort but would like to speak to anyone who may have information about this incident, specifically anyone who was queuing for the Coastguard HQ boat ride between around 11.30am and 12.45pm.
“Get in touch either by calling 101 or via our website, quoting reference number 4324 0202 786.
“Alternatively, you can provide information anonymously to independent charity Crimestoppers by calling 0800 555 111 or via its website.”
Police have confirmed they are not looking for further suspects in relation to the incident.
