The victim was attacked as she made her way to the toilets at the outdoor venue in Glasgow. She was dragged to the rear of the bloke and assaulted by one of the men whilst the other stood guard. Her ordeal only ended when three revellers walked by, saw what was happening and shouted at the pair to stop causing the offenders to run off.
The woman, who is 32-years-old was not hurt during the incident but is said to be extremely shocked at what has happened.
It occurred around 10pm on Friday and last night police appealed for the trio who witnessed the attack to come forward.
Police are appealing for information about the incident and are keen to trace the three men who shouted at the attackers.
Detective Sergeant Euan Keil said: “The woman was making her way to the toilets when she was grabbed by one man and pulled to the rear of the toilet block where another man sexually assaulted her.
“Her attackers fled when they were disturbed by three men who were walking by the area and who shouted at them.”
He added: “I don’t think the three men realised what was actually going on or that their intervention probably stopped this attack from escalating.
“It is important that we trace them as what they saw could prove vital to us catching the two men responsible.”
The two suspects are both described as white, 6ft tall, of medium build and with dark hair.
One was wearing a black T-shirt with a small logo on the front and the other a white T-shirt with black writing.
A TRNSMT festival spokesman said: “We are doing everything possible to help emergency services with their enquiries but our focus at this moment is the wellbeing of the person involved and we are ensuring that they have all the support that they need.”
*Anyone with information is asked to contact Stewart Street CID via 101 quoting incident 1094 of the 12 July 2019 or call Crimestoppers on 0800 555 111 where anonymity can be maintained.