Police are appealing for witnesses to the incident, which happened about 4pm on Thursday, 2 September.
A spokesman said: “Police received several reports of a woman being verbally and physically abusive towards a boy in the car park near the Cranleigh Medical Practice.
“A 56 year-old woman has since been arrested for assault causing actual bodily harm, but enquiries are ongoing and we are still looking for witnesses to this incident to help us identify the other parties involved.”
The boy is described as white, aged between five and seven, with cropped, dark brown hair. He was wearing a two-piece or onesie with Marvel character The Hulk on the front and long blue sleeves, said police. He was also wearing Timberland-style boots. The second woman is described as white, wearing black trousers and a white short-sleeved top with ruffles over the shoulders.
The spokesman added: “Were you in Cranleigh close to the medical practice or the high street on Thursday, 2 September at around 4pm? Did you see or hear anything that might assist our investigation? If so, we want to hear from you. Please contact us, quoting PR/45210093597 via: Webchat on our website police.uk, Online https://www.surrey.police.uk/ro/report/ocr/af/how-to-report-a-crime/, calling us on 101, if you do not wish to leave your name, please call the independent charity Crimestoppers on 0800 555 111.”