A driver who survived after her windscreen was smashed by a concrete block dropped from a bridge near Brentwood has spoken of her relief and amazement at her escape.

But a copycat attack 40 minutes later left a Harold Hill woman fighting for her life.

Lisa Horne, 26, said she believed that “somebody was looking over me” after she and her 48-year-old mother escaped unharmed when their Vauxhall Astra was targeted on the A12 in Essex on Thursday evening.

She said the perpetrator must be caught before someone is killed.

“Obviously if I was going any faster, it may have been a different story. I do feel very lucky,” she said.

Lisa said she was very shaken by the incident.

“I am scared to drive, I don’t think I will be driving in the dark. I certainly won’t be going down the A12,” she said.

“I am scared that I might never have come home to my two young children.

“It has scared me a lot and made me realise how precious life is.”

Lisa’s mother, Stella, told a news conference: “I remember seeing like a shadow coming down from the sky, and there was the biggest explosion. That was a rock hitting the car.

“At the time I thought it was something off an aeroplane, that was the first thought that was in my head.”

She said she was “so proud” of her daughter and how she handled the incident.

“I went into mum mode and started shouting,” she said.

Asked what she thought of the perpetrator, she said: “I just don’t know how they went home that night and slept, when they could have killed four people in half an hour. I can’t sleep, thinking about it.”

The block was dropped from the Fryerning Lane bridge, near Ingatestone.

A 57-year-old woman was left with fractures to her ribs and to bones in her face, plus internal injuries, when a “bucket-sized” piece of concrete was dropped on to her vehicle from a different bridge on the same stretch of road between Chelmsford and London.

That happened at 10.05pm as her car passed under West Hanningfield bridge near Galleywood.

The woman, now in a stable condition at Broomfield hospital in Essex, was a passenger in a car driven by her husband, who suffered minor cuts and bruises.

Police are treating both attacks as attempted murder.

Lisa was driving to Chelmsford with her mother after Christmas shopping at Lakeside shopping centre when the block crashed on to their windscreen.

Police investigating the attacks are trying to determine whether they have any definite links to more than 30 similar incidents on bridges along the A12 in Essex over the past three years.

Lisa said she had been travelling at 50-55mph at the time of the incident.