A security guard reportedly disappeared with £1 million after abandoning his G4S cash-in-transit van in south-west London.
The driver is said to have fled with 40 deposit boxes and left the vehicle in a residential street in Clapham on Tuesday.
Police were alerted eight hours after the blue armoured van, emblazoned with the G4S logo, was first seen parked on a double yellow line, The Sun reported.
Scotland Yard’s Flying Squad unit launched an investigation and a 36-year-old man was arrested on suspicion of theft in neighbouring Brixton on Wednesday.
A local resident in Clapham said he was suspicious after spotting the vehicle “because there are no shops here”.
He told The Sun: “I saw some strips of paper with ‘mum,’ ‘dad’ and phone numbers. That worried me in case someone had come to harm.”
A quantity of cash was recovered and G4S, a major government contractor, said there had been no “material” financial impact from the incident.
A Scotland Yard spokeswoman said: “Police were called at approximately 7pm on Tuesday, 23 April to reports of a theft of cash deposit boxes from a cash-in-transit vehicle.
“Officers attended a location in the Larkhall Rise area of Clapham where the vehicle was parked. There was no sign of forced entry to the vehicle.
“An investigation was launched by the Met’s Flying Squad and a 36-year-old man was arrested by officers on suspicion of theft at approximately 3pm on Wednesday, 24 April in SW2.
“He has been taken to a south London police station. A quantity of cash has been recovered.”
Police said inquiries were continuing into the incident.
A G4S spokeswoman said: “These incidents are extremely rare in our UK Cash business and we are working closely with the Metropolitan Police to resolve the matter. The financial impact is not material.”