Police have released CCTV footage of the shocking moments an attacker stalked and attacked a young woman in an attempted rape as she walked home.
The attack occurred at around 6.30pm in Dagenham, Essex on 6 March.
The man followed the woman off the EL2 bus before pouncing on her and pushing her to the ground.
He removed his jeans and exposed himself before the 22-year-old woman punched him in the stomach and shouted for help.
A passing driver stopped and phoned police. The suspect ran off towards Wood Lane.
The entire assault was caught on CCTV and the suspect was pictured on cameras on the bus.
He is described as a white man in his 30s with fair hair and a short brown beard. He was wearing a grey top with a white shirt underneath and blue jeans.
DC Matt James, of the sexual offences, exploitation and child abuse command, said: "The woman is very shaken from her ordeal. She was able to shout for help and use self-defence to flee from her attacker.
"We are keen to identify the man in the CCTV footage so we can speak to him about the incident. We would also urge anyone who witnessed the incident to contact us."
Anyone with information or any witnesses are urged to call police on 101 or by tweeting at @MetCC. There have been no arrests and enquiries continue.