The group tackled two members of staff, one man and one woman, as they opened up the One Stop store in Barkham Ride at about 6.15am.

They forced one member of staff to let them into the office where they stole nearly £600. The cash may have been in a yellow bag.

Police believe the gang contained four men, all wearing dark clothing and either ski masks or scarves over their faces.

One of the thieves was described as black and of a large build, another was white and slim, while a third was black and of medium built.

Bahiradhan Felvaratna, the store manager, said the police were at the store until 1.30pm.

He said: "The three men hid behind the trees opposite the school waiting for my colleagues to open the store..

"One of the men got in when the shutter was half up and he made my colleague let the others in."

The offenders left in a car, possibly a green VW Golf, towards Nine Mile Ride.

They were not seen with any weapons and the victims did not need to be taken to hospital.

Investigating officer, Sergeant Tony Jenkins of Force CID based at Reading police station said: “We are currently conducting house to house enquiries, while a scene watch also remains in place."

Anyone with information should contact police on 101 or call Crimestoppers on 0800 555111.