What have police said so far?published at 15:16 British Summer Time
15:16 BST
Police said once emergency services had arrived at the scene, a triage centre was set up at Plungar Village Hall to assess all children present at the camp.
Following an initial assessment, eight children were taken to hospital as a precaution and all have since returned home.
The force said the investigation was now being led by the East Midlands Special Operations Unit’s major incident team.
Officers remained in Stathern on Thursday, carrying out further inquiries and providing reassurance to families affected.
The force said due to the circumstances of the initial police response, it had referred itself to the Independent Office for Police Conduct (IOPC).
Det Insp Neil Holden, the senior investigating officer, said: “We understand the concern this incident will have caused to parents, guardians and the surrounding community.
“We are in contact with the parents and guardians of all children concerned.
“Please be reassured that we have several dedicated resources deployed and are working with partner agencies including children’s services to ensure full safeguarding is provided to the children involved.
“This is a complex and sensitive investigation and we will continue to provide updates to both parents and guardians and the public as and when we can.”