More than 10 children were injured and a teaching assistant suffered a broken wrist after an accident on a school trip in Nottinghamshire.
Students from Halam Church of England Primary School, aged four and five, suffered cuts and bruises after the trailer they were in became detached from the tractor it was being pulled by on Friday.
Parents were informed of the accident within 20 minutes by staff at the school. Police are now investigating the incident, and while the Health and Safety Executive were also informed, they are not investigating but are assisting police.
A spokeswoman for Nottinghamshire Police said: "Police attended an incident in Carvers Hollow, Edingley, at around 10am on Friday. It involved a number of primary school children and staff travelling on a trailer being pulled by a tractor.
"A woman was taken to hospital with a suspected serious injury. Three others, including one child, were also treated at hospital for minor injuries. Officers are investigating the circumstances surrounding the incident, with specialist technical support from the Health and Safety Executive."
Paul Nolan, Acting head teacher at Halam Church of England Primary School, said: "We are very sorry this unfortunate incident happened and we wish the children and adults who were injured a speedy recovery. This incident has affected the whole community and everyone is supporting each other as a result."
Marion Clay, Nottinghamshire County Council's acting service director for education standards, added: "This is an established trip for reception pupils and as far as we know at this time, all the appropriate procedures were carried out. Parents of children on the trip were notified immediately of the incident as was the health and safety team at the County Council.
"We wish those who were injured in the incident a quick recovery. The head teacher will ensure that parents and carers continue to be updated over the coming days."