Major Crime Squad officers have been drafted in to hunt men who stole thousands of pounds at gunpoint from a Post Office van in Eastbourne.
A police spokesman said the squad would be taking over the investigation into the robbery on Monday of last week.
Three men wearing balaclavas lay in wait for the van as it pulled up to a side entrance of the Asda supermarket at the Crumbles Retail Park, on the outskirts of Eastbourne, which has a Post Office counter inside.
The men, one brandishing a gun, demanded money from an office inside the building but when this was refused they stole boxes from the back of the Post Office van.
Police refused to confirm how much had been stolen but described it as a "substantial amount". The trio sped away in a maroon coloured car.
A Vauxhall Cavalier, registration K140 ATX, which was earlier reported stolen was found abandoned near the Martello Inn, Langney some time later and removed for forensic examination.
No arrests have yet been made but police say there are a number of avenues to be explored.
A spokesman said: "The officers from the Major Crime Squad will come and focus entirely on this case and act as a dedicated team for this crime.
"They will be following a number of leads to this robbery."
The squad deals with crimes ranging from murder to child abduction.
Anyone with information about the robbery is asked to contact Sussex Police on 0845 6070999.
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