Police are investigating reports that a 17-year-old girl was subjected to a 'sexual offence' in Macclesfield's Victoria Park.
Officers were called at 4.50am this morning and are currently investigating the circumstances and supporting the victim.
Detective Inspector David Moores said: "We are working hard to establish the circumstances surrounding the incident and officers are in the area to provide reassurance to the local community.
"We want to take the opportunity to urge people to follow basic safety advice when out and about - remain vigilant when walking alone especially at night, maintain an awareness of your surroundings and try and stick to well-lit areas."
The whole park is currently cordoned off with PCSOs talking to people nearby.
A passer by who was walking on Fence Avenue, but wanted to be anonymous said: "I walked past on my way to worm this morning at 7.45am and there was a police cordon around a section of trees near the bandstand, but not all this.
"Now they've blocked off the whole park.
"This park used to be bad when the Vicky Park flats were here but I didn't think it was too bad anymore."
A resident, who did not want to be named but came to the park after hearing about the cordon, said: "It's a shock, this park is pretty safe, with kids playing and things like that.
"My girlfriend lives nearby, if it's a sexual assault it's very worrying."
A 33-year-old woman who lives nearby in a flat on York Street, said: "It's shocking to hear what's happened, so close to where I live.
"We had a letter through about antisocial behaviour in the park a while back but a sexual offence that's really worrying.
"I thought the park was pretty safe.
"There's no way I'd walk through there at night now."
A resident of York Street, who did not want to be named, said: "We've had police here this morning asking if we saw anything.
"We've heard about drug dealing going on and there as people that come in to the park and hang around late at night but generally the park is pretty safe.
"It's awful to hear a young girl's been attacked. It's shocking to see the whole area cordoned off.
"It's a strange time for an incident like that, at that time of the morning"
Anyone with any information is asked to contact Cheshire Police on 101 quoting incident 85 of 13 October. Information can also be passed on anonymously by calling Crimestoppers on 0800 555 111.