A woman was grabbed from behind and attacked by a group of men while she was out jogging.
Cait Smith, 23, was running at around 10pm on Tuesday in Castle Park in Colchester, Essex, when three men attacked her.
The admin assistant suffered bruises to her arms, and scrapes and bruises on her face, as well as a swollen black eye from having her head "smashed" against the ground.
Smith said: "I had stopped running for a moment to change my music on my phone, and I got grabbed from behind - I didn't even see it coming at all.
"I was wrestled to the ground, and one of the men was sat on top of me, while another was holding my head to the floor.
"I've been left with a big lump on my face from where they smashed my head to the ground."
Smith said there were no other people around to come to her rescue.
But she added: "I'm lucky that I'm quite feisty - I can hold myself in a fight.
"I don't think they were expecting me to fight back - so I just fought as hard as I could and then legged it away from them.
"I don't live that far from the park, so I was able to just get myself back home.
"But if it was any other person it happened to, maybe someone a bit more vulnerable, they might not have been as lucky as me."
She is now warning other young women and men to be aware of the "dangers" of going out in the dark alone.
Smith said: "It's terrifying that other young people like me should have to live by a different clock out of fear.
"But that is what I want other people - not just women, but everyone - to be aware of. I don't want this to happen to anyone else.
"From now on, when I feel able to go out running again, I'll be sticking to busier areas."
She has been flooded with thousands of messages and comments of support since posting on Facebook on Wednesday morning about the assault.
Essex Police confirmed they were investigating the incident after receiving a complaint from Smith.
Chief Inspector Jon Evans, District Commander for Colchester said: “I understand this will be a concerning incident for people living across Colchester and use Castle Park.
“No one should feel afraid for their safety when going out alone but we are working to identify those involved.
“Fortunately incidents such as this a rare in Colchester but we have additional patrols in the area to provide some additional reassurance.”
Police have asked anyone with information to contact them.