Three armed robbers may be red handed with a skin staining dye released from a security box stolen at gunpoint.

A security guard was attacked from behind as he approached Carpenders Park Post Office, in Delta Gain, South Oxhey, on Monday, 3 February.

The guard was threatened with a hand gun before he handed over the security box, which was found later by police in Harrow.

The box was fitted with a security device which released a red dye. This can stain clothes and skin for up to three months.

Two of the three men involved in the robbery jumped the guard at 9am on Monday.

The offenders made off in a maroon Vauxhall Cavalier down Delta Gain to Compton Place. They then abandoned the vehicle and switched to a dark blue Mercedes saloon.