Moped riders staged a smash-and-grab raid at high-end jewellers Tiffany & Co making off with a “significant amount of items”.
Police were called at 2.56am on Friday to reports that a transit van had driven into the front of the luxury jewellers in Sloane Street, west London.
Scotland Yard said a number of people on mopeds had then stolen “a significant amount” of items from the shop window.
Smashed glass display cases could be seen inside through the cracked window which had been rammed off its frame.
The raiders then fled on mopeds, leaving the van behind at the scene, the force added.
Detective Inspector David Watkinson said the force was particularly keen to speak to motorists who might have caught the overnight raid on dash-cam footage.
He added: “This was a brazen and targeted incident which has resulted in a significant amount of items stolen.
“Although the incident took place overnight, it is a busy well-lit area.
“Did you see the incident take place? Or perhaps you saw any of the vehicles involved, if so we need you get in touch to assist our investigation.
“We are particularly keen to hear from passing motorists who may have captured what took place on dash-cam footage.”
No arrests have been made.
An employee at the store told the Press Association the company was working with police on their inquiries, but could not comment further.
In a statement Tiffany & Co said: “Even more precious than jewellery, safety is our top concern when incidents like these occur, and we are relieved to know that no-one was injured.
“While we cannot comment on what may have been taken or its value, we are working closely with the authorities in this ongoing investigation.”
Police initially cordoned off the store, but the barriers were lifted on Friday afternoon.
Anyone with any information should call police on 101 quoting reference CAD 0671/26Apr.