A have-a-go hero chased down a man suspected of repeatedly punching and sexually assaulting a woman while filming the incident on his phone.
Scotland Yard said the 20-year-old victim was "traumatised" and suffered facial injuries in the attack as they released the footage of the incident in Tottenham, north London. Investigators believe her attacker may be linked to two other assaults on women in the area.
In the footage, the man can be seen running, before he tackles the suspect to the ground.
Wearing a red baseball hat, blue jeans, white trainers with a black leather rucksack on his back, the suspect was holding at least one sports racquet.
He was able to get up and after words were exchanged, he ran away.
The was attacked in broad daylight as she walked down the street on 4 April, London's Metropolitan Police said in a statement.
After sexually assaulting her, her attacker punched her around five times in the upper body and face.
She was left traumatised and "sustained swelling and pain to her eye” from the attack, which was witnessed by a passing motorist who intervened, the force added.
Detective inspector Paul Ridley said the attack might be linked to two other similar crimes in the area.
During the first incident also on 3 April, a man approached a 25-year-old woman was approached by a man she did not know who attempted to speak with her.
As she was wearing headphones, she could not hear what he was saying. The man began swearing an gesticulating at her, before he kicked her and fled the scene.
Police have also released CCTV footage of that incident.
A 27-year-old woman was also sexually assaulted on the morning of 4 April, before the man punched her in the face and fled.
Detectives described the suspect as a black male of slim to medium build.
“All the offences are clearly sexually motivated and the random nature, additional violence and aggressive behaviour by the assailant towards these young women is concerning,” detective inspector Ridley said. “The incidents have occurred within a very close proximity, two in the same street within minutes of each other. The women were understandably left extremely distraught.
“There is always a possibility that the suspect may have followed other women in the area, perhaps making only minimal or even no contact.”
He added: “I would therefore urge anyone who may have been assaulted but has not reported it, or who has seen a male matching the description of the attacker to approach the investigation team. You may hold vital information.”
Police have asked those in the area to remain vigilant and to contact them immediately if they have any concerns.
Anyone with information that could assist the investigation is urged to contact North Area CID via 101, or by tweeting @MetCC quoting: Operation Carrera. Information can also be reported anonymously to the charity Crimestoppers on 0800 555 111 or via their non-traceable online form at www.crimestoppers-uk.org.