Horrified diners at a fast-food restaurant looked on as a security guard was robbed outside.

The female guard had been picking up the night's takings from McDonald's, in Barkby Thorpe Lane, Thurmaston, at about 10.20am yesterday when the robbery happened.

One witness described hearing a scream and then seeing a man with a hood over his head using a weapon to threaten the guard, who dropped her cash box.

The police were called but the robbers managed to make off with the cash using a vehicle parked nearby.

The robbery is the fourth of its kind since September 29.

Witness Susan Mitchell, a delivery driver, was parked opposite the white Loomis security van when the robbery happened.

She said: "I was sat in the van eating my breakfast when I heard a scream.

"The security woman had just come outside with the money from McDonald's and she was about to put it in the van when he approached her and threatened her. He was holding something in both his hands but I couldn't see what it was.

"Then she dropped the box and he picked it up and ran off to a vehicle on the main road. It was all over so quickly and it was so surreal."

Staff at other businesses in the road looked on as police swarmed around the area and the McDonald's car park was cordoned off.

Mohsin Ahmed, who works at Dunelm Mill, said: "There was a vehicle parked up on the main road before it all happened and I remember thinking that was a bit suspicious, because it shouldn't have been there.

"Then the next thing I knew, the police helicopter was overhead."

A Loomis spokesman confirmed that the female guard was working alone at the time of the robbery and that an amount of cash was taken.

He said: "She's not hurt but she's shaken. We deplore this kind of criminal activity and we are working with the police."

Similar robberies against security guards have taken place over recent weeks. On Thursday, October 9, a guard was robbed outside the Iceland store, in Saffron Lane, Leicester.

Just one day before, there was a similar incident in nearby Southfields Drive.

On Monday, September 29, two masked robbers escaped with thousands of pounds after attacking a security guard in Eyres Monsell, Leicester.

Police say they are not linking the robberies at this stage.

Officers have appealed for witnesses to the latest robbery to come forward. It remains unclear what weapon was used.

A spokesman said: "Police were called at 10.19am on Thursday after reports of a robbery in Barkby Thorpe Lane, in Thurmaston.

"It is believed the driver of a security van was robbed of a cash box after being threatened. No-one was injured.

"We are appealing for any witnesses to get in touch."

McDonald's said it could not provide any further information.

Witnesses are urged to call police on 0116 222 2222 or Crimestoppers anonymously on 0800 555 111.