Families were queuing for a popular Legoland attraction when a little boy in a pram went into cardiac arrest, shocked witnesses have revealed.
Police say the child remains in critical condition, while a 27-year-old woman who was arrested has been released on bail.
The five-month-old boy was rushed to hospital last Thursday after the incident at the tourist attraction in Windsor, Berkshire.
Theme park staff have now told MailOnline of their distress after seeing what happened near a queue for the park's Lego Coastguard HQ ride.
A woman from Witham, Essex, was arrested on Saturday on suspicion of failing to cause unnecessary harm.
A woman has been arrested on suspicion of neglect after a five-month-old boy went into cardiac arrest at the Legoland Windsor Resort (file image)
The boy suffered cardiac arrest last Thursday afternoon near the headquarters of the Lego Coast Guard
She has been released on bail until April 26.
A Legoland employee told MailOnline how the disturbing scenes unfolded as people queued for the nearby Lego Coastguard headquarters attraction, one of the site's most popular locations.
They said: 'The whole area around the ride was cordoned off. Guests and staff were asked to leave the area and barriers were placed to prevent anyone from entering.
'Other attractions in the area were also closed. It sounds dramatic, but the people were calm.
'I saw two ambulances driving towards the ride and one of the vehicles parked directly outside the make-up stand.
'I did not see what happened, but I was told that there had been an incident in or around the queue for the Coast Guard ride.
“The baby boy was in a stroller at the time and there was a woman with him – I don't know if she is the same person who was later arrested.
'I couldn't see any police from where I worked, so I don't know if they actually spoke to her in the park.
The Coast Guard Headquarters (pictured) is a popular attraction at Legoland Windsor Resort and police are asking people queuing to come forward if they have any information about the incident
An amusement park employee told MailOnline that the incident did not occur during the ride itself
'I believe the police have been checking the CCTV footage since the incident.'
The worker himself described the ride as 'very peaceful' and said there is 'no height restriction, although young children must of course be accompanied by an adult'.
Riders must be at least 1.3 meters tall to participate in the ride if not accompanied by an adult or 'responsible person' who is at least 16 years old.
Legoland advises that guests are required to press the pedals and steer the boat, adding that drivers may get wet during the ride.
The staff member added: 'I don't think anything happened during the ride itself, it wasn't like the boy fell into the water or anything like that though.
'It's a slow boat ride, with the occasional jet of water in certain places.
“I just hope the little boy comes through okay.”
Officials at Legoland declined to comment on the incident today.
The attraction at Legoland UK is described as a 'gentle water ride' (file photo)
Riders must be at least 1.3m (4ft 4in) to participate in the ride if not accompanied by an adult or 'responsible person' at least 16 years old
A manager said: 'The incident is part of an ongoing police investigation so for that reason we are not saying anything at this time.'
According to Thames Valley Police, the baby remains in a critical condition in hospital following the incident at around 1pm last Thursday.
Investigating officer Detective Constable Zoe Eele, from Thames Valley Police Child Abuse Investigation Unit, said: “We are investigating a distressing incident involving a very young child at Legoland Windsor earlier this week.
'First and foremost, our thoughts go out to the family of the boy who is in a critical condition in hospital after suffering cardiac arrest. We support them as best we can during this extremely difficult time.
'We are working closely with the team at Legoland Windsor Resort but would like to speak to anyone who has information about this incident, particularly anyone who was queuing for the boat ride at Coastguard Headquarters between 11.30am and 12.45pm.'
She urged anyone with information to call 101 or contact police via the website, quoting reference number 43240202786 0 – or alternatively provide information anonymously to the independent charity Crimestoppers on 0800 555111 or online.
Ms Eele added: “We have made an arrest in connection with this incident and are not looking for anyone else as a suspect.
'I would ask the public to avoid speculation about the incident and respect the boy's family at this very disturbing time.'
The first Legoland theme park, in Billund in Denmark, opened in June 1968 (archive photo)
Legoland in Windsor has become the country's most visited theme park in recent years, attracting 2.43 million people in 2022.
It first opened in March 1996, following the success of the first Legoland park in Billund in Denmark.
The Windsor theme park is open from March to January and currently offers 55 different attractions, including three roller coasters and six water attractions.
The location was previously home to Windsor Safari Park from 1969 until its closure in 1992.