Well-wishers have raised more than £20,000 to support the “extraordinary” Sarah Doone, who lost a leg after being run over by a cement truck on the Old Street roundabout on July 25.

So far the initiative has raised £20,804 in seven days and is well on its way to reaching the £25,000 goal.

Sarah, who works with Aljazeera, was knocked off her bike at about 3.30pm and was airlifted to hospital, where doctors were forced to amputate her left leg but managed to save the right.

Her friends and colleagues started the Go Fund Me page to support Sarah, who as a freelancer will now be without an income, during the coming months of rehabilitation, physiotherapy and additional treatment.

Charlotte Dewsnap, who has worked with Sarah at Aljazeera for the past eight years, told the Gazette: “The way she has dealt with it is amazing. She is just so full of life and it has not got her down. Sarah is extraordinary.”

She said their initial target was to raise £5,000 in a week but the crowdfunder exceeded that target in just four hours.

“But that just goes to show how much love there is for Sarah and what an amazing person she is,” Charlotte added. “We are delighted with what we have raised so far but we hopefully we can continue to exceed our targets.”

She said Sarah is a massive Justin Bieber fan, so the office filmed a video of all her colleagues singing along to one of his tunes and sent it to her.

Charlotte added: “We wanted to do something to make her smile and it made everyone laugh for a long time. Everyone wanted to be involved.

“We really just hope to raise as much money as possible.”

Addressing potential donors, she added: “Please get involved even if you don’t know her. A lot of people have been donating just because they think she sounds awesome.”

BBC journalist Jeremy Vine, whose bike-mounted footage of a road rage incident went viral last year and led to a driver being convicted of assault, is reportedly among the donors.

You can support the Friends of Sarah page at gofundme.com/friends-of-sarah.