Large numbers of people had gathered in the park yesterday during the hot weather.
Shortly after midnight, police received a report that an 18-year-old woman had been raped at around 11.30pm.
It is reported that the incident occurred in a silver or grey Mercedes which had been parked in one of the spaces at the entrance to the park. Afterwards, the suspect left the scene in the car in the direction of Hunter's Bar roundabout.
The suspect is described as Asian, aged in his 20s, wearing a white T-shirt and black joggers or jeans.
Superintendent Simon Verrall said: “We know the community is already concerned about the events that unfolded in Endcliffe Park last night and this incident is particularly upsetting.
“Patrols are in place in the park throughout today, into the evening and in the coming days as we head into the Easter bank holiday weekend. We are working hard with our partners to address the wider issues we have seen and if anybody has any concerns, please do not hesitate to approach one of our officers. They are there to make you feel safe and to help people to enjoy Sheffield’s outdoor spaces appropriately and safely.”
Anyone with information is asked to call South Yorkshire Police on 101 quoting incident number 13 of 31 March.
Sheffield City Council confirmed today that they had cleared seven tonnes of rubbish from the park following a day and evening of heatwave 'chaos' and partying which also saw the Mi Amigo war memorial damaged. Several small fires were started and a 17-year-old boy was arrested for affray following a fight between a group of people.