Armed police raced to Sarratt this afternoon after a man with a concealed weapon snatched a bag from a woman, officers said.

Police cars cordoned off both ends of Deadman’s Ash Lane just after 12.30pm and armed police officers and a helicopter arrived minutes later.

Hertfordshire Constabulary said a man threatened a woman and he had a concealed weapon at the time of the incident. Officers confirmed the woman was not injured, despite her bag being taken.

No arrests have been made after the man ran off in an unknown direction.

One neighbour, who asked to remain anonymous, said: “Deadman’s Ash Lane was closed by normal Watford police cars at both ends of the road. Then minutes later, there was a helicopter flying above the road.

“Soon after that, there were four big Volvos, not the usual type of police cars you see round here and there were policemen standing around with big machine guns. It was a full armed response.

“I was worried at first because they had closed our road down. When I first tried to go down the road, they said they cannot give any information about what is going on because it is a live incident.

“We could see the helicopter hovering near our house, but then we realised it had just angled itself to watch what was happening across the road”.

Investigators said the man is described as a black man, with a very thin face, approximately 5ft 8in tall, aged around 35 and of thin to medium build.

He was said to be wearing dark blue clothing and a dark blue beanie hat with a lighter blue band around it.

“Detective Inspector Phil Moss said: “We are doing all we can to trace the person responsible and I would ask that anyone who was in the area at the time and saw anything suspicious, or who has any other information about what happened, contacts police immediately via the non-emergency number 101.