THUGS attacked and robbed a security guard delivering cash to a busy supermarket before fleeing in a high-powered car.

Minutes later, the men broke open the stolen cash box with a sledgehammer, behind a primary school.

They escaped, possibly covered in red anti-theft dye, in a getaway car.

"We're particularly keen to speak to witnesses who saw the incident at Asda, in Halton Lea, or who have seen their second vehicle," said investigating officer Det Con Spaven, from Runcorn Police's robbery unit.

The security firm guard was robbed as he entered the Asda foyer to load the store's external cash machines from the inside.

Two men got out of a black N-reg Subaru Impreza, driven by a third man, and approached him from behind.

They punched him to the ground and grabbed the cash box he had dropped before fleeing.

The gang then abandoned the vehicle near Castle View Primary School, in Halton Brook, and, huddled in a footpath behind the school, attacked the cash box with a sledgehammer.

Police say this triggered an anti-theft mechanism, which exploded red dye over the bank notes and, possibly, the men.

Panicked, the trio then fled the scene in a maroon or red N-reg Volvo parked nearby and were last spotted heading towards Boston Avenue.

"We suspect they didn't run very far but went straight to their second vehicle," DC Spaven added.

The first man is described as white, stocky, around 5ft 10ins tall, and wearing a dark, long-sleeved top and cap.

His accomplice was also white and stocky but taller, and was wearing a white, long-sleeved top, dark trousers and baseball cap.

The driver of the Subaru was wearing dark clothing.

Police say the security guard was left shaken but not seriously injured.

Anyone with information about the incident, which took place last Monday, June 19, at 8.40am should contact DC Spaven on 01244-613 730 or Crimestoppers anonymously on 0800-555 111.