The police helicopter was scrambled and sirens blared as a high speed chase ensued through the streets of Milngavie.

Around 3pm a masked man pulled open the door of the woman's Audi car, thrust a knife at her and demanded she get out of the vehicle as she was leaving the petrol station on Glasgow Road.

Speaking to the Herald after her ordeal, the woman said: "If it had been dark I would have known to have my car doors locked — but it was in the middle of the afternoon and the filling station was busy.

"I was positioned to turn right on to Glasgow Road and had been checking traffic coming from my left. As I turned back to look right I jumped with fright at the masked face at my window and before I knew what was happening the car door was wrenched open and brandishing the knife the man ordered me from my car.

"One driver in the forecourt had seen the man pull the balaclava over his face as he got near my car and he made to came forward to see if he could help me, but I had to shout to him that the man had a knife and in that few seconds of distraction I got out of the car and the thief got in and sped off as people were calling the police.

"It all happened so fast — drivers in the forecourt were saying they couldn't believe it had happened before their eyes in broad daylight."

Moments later police officers heading along Strathblane Road saw the Audi being driven at a reckless speed and began to pursue it. Officers said the thief, realising he was being chased, drove even faster and narrowly missed cars as he overtook on the wrong side of the road in his bid to escape.

He drove up Park Road and headed into Prestonfield where he parked and locked the car but was able to make good his escape before officers in the van could catch up with him.

As well as the helicopter, the dog branch was summoned to the scene but the search area was contaminated because of the volume of parents and children on the streets from the nearby primary school.

Police have issued a limited description of the man who is believed to be between 18 to 25, wearing a blue/grey tracksuit and around 5ft 10ins in height.

Anyone with information should contact Milngavie police office on 0141 532 4000.