A boy (9) who fell from the emergency exit of a moving coach in England may have been queuing for the toilet at the time of the accident, police say.
The boy remains in a critical condition after falling from the vehicle as it travelled on the A47 near King's Lynn on Sunday.
The coach was carrying 20 children and 10 adults to Lincolnshire after the youngsters had played in a rugby tournament at Holt in north Norfolk.
The boy was initially taken to the Queen Elizabeth Hospital in King's Lynn and later transferred to Addenbrooke's Hospital in Cambridge last night.
Police say the boy's father was travelling on the 71-seater double-decker coach, while his mother was travelling in a car as part of the convoy. The coach party were members of Stamford Rugby Club.
Inspector Chris Brooks said "This is a very difficult time for the boy's family and we have specially trained officers supporting them. We've already interviewed some of the passengers on board as well as drivers who were in the area at the time of the incident".
"As a result of initial enquiries we know just prior to the incident that people were queuing for the toilet. Somehow, the door has opened and the boy has fallen from the moving coach".
"The coach was recovered yesterday and is being kept in a secure compound. The vehicle will be examined by police and VOSA investigators and this is the focus of our enquiry at this stage".
"We will also be speaking to other people who were on board at the time of the incident and it would be inappropriate to speculate on possible causes at this stage" he added.
