Two men - one wearing a horror mask - held a schoolboy at knifepoint in a bid to raid a mid-Essex petrol station.

They burst into Jones of Chelmsford in Baddow Road carrying long kitchen knives. One was wearing a balaclava while the other had on a horror mask, like the one in the horror spoof Scream.

They held a knife to the throat of schoolboy Shawn Roberts, 16, of Moulsham Lodge, who was working as a Saturday helper cleaning and selling lottery tickets, and ordered him behind the counter and demanded he opened the till.

Meanwhile they forced a cashier to lay face down on the floor.

Shawn tried to open the till but did not know how.

But the raid was foiled when a motorist pulled on to the forecourt and scared the robbers away.

Shawn's mum Sue Roberts, manager of the service station, yesterday (Tuesday) praised her brave son.

Mrs Roberts was alerted by a passerby who saw two men running from the premises.

She said: "Saturday is the only day we have two people on, because it's usually so busy.

"When I got the call to say there was an attempted robbery I knew nothing about the knives. I rushed down there.

"It frightened me when I thought of some thug holding a knife to my son's throat but I was surprised by the way they handled it, they were shaken but not too bad.

"They did exactly the right thing. If someone armed tries to rob the till company policy directs employees to hand over the cash.

"The experience has not turned either of them away from working at the service station."

The incident happened just before closing time on Saturday.

The men were described as in their late teens, slim to medium build and dressed in dark clothing. No-one was hurt and no money was stolen.

Anyone with information should contact Det Con Marc Barry at Chelmsford CID on 01245 491212 or Crimestoppers on 0800 555111

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