ARMED robbers posed as police officers to steal a van containing £400,000 worth of computer equipment.
A gang set up a fake police checkpoint in Stanwell Road, Feltham near the junction with the A30 last and stopped a silver Ford Transit carrying the high-tech equipment.
They sprayed the driver and the passenger with CS gas and threatened them with an electrical Taser gun similar to those used by riot police to stun protesters.
The four attackers, who were dressed in high-visibility jackets and police-style caps, then climbed into the van, leaving the victims on the side of the road.
The Transit was found later, empty and abandoned in Stanwell Moor. Police believe a dark BMW 5 series and a dark coloured Audi A4 saloon were also involved in the robbery and are appealing for anyone with information or who was in the area between 11pm and 11.30pm on Monday November 9 to come forward.
Detective Sergeant Ian Wilson said: "This was a well-organised and targeted attack aimed at a specific vehicle that the robbers knew would be carrying a high-value consignment.
"These criminals were not afraid to use violence to carry out the robbery and the experience has left the driver and his passenger very shaken."
Anyone with information should call police on 020 8246 9972 Crimestoppers anonymously on 0800 555 111.