A pensioner was seriously injured after being assaulted and robbed of the 4,000 euro (£2,895) he had just exchanged ahead of a holiday.
Police described the attack on the 84-year-old man as "sickening" and said they suspect the person responsible had targeted the victim, following him from the money exchange shop he had just been to.
The man remains in a serious but stable condition in hospital, the Metropolitan Police said, and is awaiting surgery for a broken leg after the incident at Wades Hill, Enfield, north London on Saturday afternoon.
The suspect, described as an Eastern European man in his mid to late 20s, of medium build with short black hair and a moustache, left the scene in a grey Audi car.
Detective Constable John McCarthy, from Enfield CID, said:
This was a vicious and sickening attack on a vulnerable elderly man who had exchanged money ahead of a holiday with his wife. There is a strong indication that he was targeted and followed by the suspect from the money exchange shop in Oakwood.
A police officer has been disciplined after he posted a "joke" on Facebook about sexual assaults by Rolf Harris.
The Metropolitan Police constable was handed a final written warning about his internet activity by bosses last year.
A Freedom of Information response from the force said the officer "posted a joke about sexual assaults on minors by Rolf Harris".
The PC also "openly criticised" the force and posted a status about police community support officers which "attracted a number of negative comments from friends".
Scotland Yard confirmed that a misconduct hearing took place in December in which a Pc faced allegations related to the posting of inappropriate comments on social media.
The panel found an allegation of "discreditable conduct" was proved. The officer, who has not been identified, remains in his post.
Home Secretary Theresa May has established an inquiry into undercover policing and the operation of the Metropolitan Police's Special Demonstration Squad, to be led by judge Lord Justice Pitchford.
A masked mob pelted police with missiles as they attended the scene of a stabbing.
The "volatile" crowd of around 30 people covered their faces and threw bottles at officers during the incident in Hackney last night.
Police were called to Chatsworth Road at around 11.30pm after an 18-year-old man suffered stab wounds to his upper body.
No officers were injured during the trouble, while one pursued and apprehended a suspect "despite continuing threats from a volatile crowd", a Metropolitan Police spokesperson said.
Some 11 people "will be interviewed as witnesses" by the police searching for missing Madeleine McCann, Good Morning Britain heard.
British and Portuguese "men and women" are expected to be quizzed by the police over what happened to the missing youngster.
Four men arrested in connection with an alleged Islamist terror plot just two days before Remembrance Sunday will be held for a further seven days.
Counter-terror police detained the men, aged 19 to 27, on Thursday night at locations across west London and High Wycombe in the Thames Valley area, Scotland Yard said.
Several properties across the south east of England are being searched as part of an ongoing investigation into Islamist-related terrorism.
Four men remain in custody after being held overnight during raids across Thames Valley and west London in relation to an alleged terror plot.
One of the men, a 19-year-old arrested at an address in High Wycombe, has been named locally as Yousaf Syed.
His friend told ITV News he was a "really nice guy" and accused officers of "demonising" the Muslim community.
ITV News UK Editor Rohit Kachroo reports from High Wycombe:
A 19-year-old man arrested at an address in High Wycombe by counter-terrorism officers is Yousaf Syed, ITV News understands.
He was one of four men arrested across Thames Valley and west London overnight in relation to an alleged Islamist terror plot.
Eight addresses across Thames Valley and west London are being searched as part of an ongoing investigation into Islamist-related terrorism, Scotland Yard has said.
Searches are taking place at three properties in High Wycombe along with addresses in Greenford, Hounslow, Hayes, Southall and Uxbridge.
Police confirmed four men arrested overnight in relation to an alleged Islamist terror plot remain in custody pending further enquiries.
The Metropolitan Police statement confirmed officers from Counter Terrorism Command were "working closely" with their colleagues in SE Counter Terrorism Unit and MI5.
A window pane at the door of one of the properties in High Wycombe searched by counter-terror police has been seen cracked after the initial raid.
Four men were held in Thames Valley and west London in connection with an alleged Islamist terror plot.