Officers first became aware of the event after receiving reports at around 2pm on Sunday 19 July 2020 from members of the public about a large gathering involving vehicles on an industrial estate off Windmill Lane.
Responding officers attended the scene and monitored the situation.
Due the risk of public order being potentially increased by intervening and dispersing the event – as well as patrols responding to in excess of 90 incidents across the district – officers continued to survey the scene.
An investigation into the organisation of the event is underway.
No arrests have yet been made and enquiries are ongoing.
Superintendent Jane Higham, of GMP’s Tameside district, said: “The scenes that were posted on social media of the car event in Denton on Sunday (19 July) afternoon were quite frankly unacceptable and we are committed to finding out how this incident came to be.
“The disruption caused by the large gathering of people and the volume of traffic wreaked havoc across some of the main routes in the town and impacted the nearby motorway network. This disregard for the rest of the public is shocking and will not be tolerated.
“While I completely understand and empathise with the many people affected by this event and concerned with our response, it is important to recognise that we only became aware of the event once it had begun and the risk posed to our officers and the wider public by trying to intervene after this was considerably enhanced.
“This weekend on the Tameside district an illegal rave was prevented from taking place after our officers responded to public-led intelligence; what we need to continue to ensure is that anyone with information about such large illegal gatherings contacts us with any details they have so that we can enforce police powers before they escalate into events that are complex and unsafe to try and repress.
“We have met with the local authority today (Monday 20 July 2020) to debrief the incident and are planning how we take preventative measures in the future as well as identifying and taking to task those involved in coordinating this event. In the meantime, I urge anyone with information about this event or future events of this nature to contact police via 101 or online immediately.”
Anyone with any information should contact police on 101 quoting incident number 1748 of 19/07/2020. Details can also be passed anonymously to the independent charity Crimestoppers on 0800 555 111.