Four children have been taken to hospital after eating jelly sweets which they believed contained cannabis.
Surrey Police said three children suffered "a violent reaction" and were left vomiting uncontrollably and falling in and out of consciousness.
As well as the 12-year-old girl, 12-year-old boy and a boy aged 13 who suffered the adverse reactions and were taken to hospital by ambulance, a 12-year-old boy was taken to hospital by his family as a precaution because he is also believed to have eaten the sweets.
Police said they were called by the South East Coast Ambulance service to the parade of shops on Pound Lane, Epsom, where the three children were found ill.
All four children will remain in hospital overnight for observation.
There is a suggestion that the sweets may have been supplied to the children at the nearby Court Recreation Ground.
Police do not have a clear description of the sweets involved, although a similar report from Friday night involved "jelly apple rings" which appear as green jelly circles.
Police believe the sweets may be "edibles" - food containing cannabis extract.
Detective Sergeant Lee Marks, of Surrey Police, said: "We are, of course, trying to understand what these sweets are, where they came from and what they contain.
"However, our immediate priority is to warn parents; and to tell children in the area not to be tempted to try them as they are obviously causing substantial harm.
"These types of products, which may be marketed as 'cannabis-infused' or 'CBD-infused' are illegal, and therefore unregulated, in the UK.
"They can appear to be commercial products with professional packaging, but this should not be taken as a sign that they are safe or legal."
Surrey Police are asking anyone with information about the supply of these sweets or anyone who has found similar items or related packaging in the area near Court Recreation Ground to not destroy them, and to contact the force on the online chat on their website, quoting reference PR/P21090934.