A pensioner has been arrested on suspicion of administering poison at a summer camp, which led to eight children being taken to hospital.
Leicestershire Police said it received a report of children "feeling unwell" at a camp in the village of Stathern on Sunday, July 27.
A triage centre was set up at a village hall nearby to the camp at Stathern Lodge in Canal Lane.
After being assessed by ambulance crews, eight children were taken to hospital "as a precaution" and have since been discharged, the force has confirmed.
A 76-year-old man was arrested at the camp on suspicion of administering poison/a noxious thing with intent to injure/aggrieve/annoy.
He remains in police custody.
Detective Inspector Neil Holden, the senior investigating officer, said in a statement: "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.
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Police received reports of children feeling unwell at a summer camp on Canal Lane in the village of Stathern
|"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.
"We also remain at the scene to carry out enquiries into the circumstances of what has happened and to continue to provide advice and support in the area.
"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."
Leicestershire Police said it has referred itself to the Independent Office for Police Conduct (IOPC) "due to the circumstances of the initial police response".
An IOPC spokesperson said: "We received a conduct referral on Tuesday, July 29, from Leicestershire Police relating to their handling of concerns passed to them over the wellbeing of a group of children.
"Our assessment team has examined all available evidence and concluded the matter should be independently investigated by the IOPC.
"The investigation will look at whether there were any breaches of professional behaviour – namely a failure to carry out duties and responsibilities – that resulted in a delay in Leicestershire Police’s response to what was later declared a critical incident."