(CNN) -- Donations to the fundraising page of a young woman who died less than one mile (1.6km) from the London Marathon finishing line, are heading towards the $1 million mark.
As news of Claire Squires' death spread across social media sites, so too did the link to her Just Giving fundraising page, sparking a flurry of donations reaching more than £400,000 ($650,000) and rising fast by Tuesday afternoon.
The hairdresser, from North Kilworth in Leicestershire, died near St James's Park on the final stretch of the 26.2 mile (42km) course on Sunday.
The 30-year-old, who had climbed Mount Kilimanjaro just last month, collapsed as she ran up Birdcage Walk -- the final stretch covered by competitors before reaching Buckingham Palace and turning on to The Mall.
Paramedics were unable to revive her and she died at the scene. The cause of death is not yet known.
News of the tragedy quickly spread on Twitter and Facebook, helping prompt a flood of donations to her chosen charity, the Samaritans.
The donations, which initially stood at £500 ($800), surged throughout Monday and Tuesday as publicity spread through social and conventional media sources.
Almost 40,000 donations have been made on Squires' fundraising page, with many people including heartfelt messages of sympathy to the tragic woman's family.
She had chosen to run for the Samaritans after her mother Cilla volunteered with the charity for 24 years.
She had posted on her fundraising page: "hi guys as you all know i am running the london marathon it was just going to be for fun. but its a fab opportunity to raise money for my charity the samaritans if everyone i know could donate £5.00 ($8) that would be a great help and change lives."
Catherine Johnstone, chief executive of the Samaritans, said the charity had been overwhelmed by the response.
"We desperately wish that it was not under these circumstances but we have been overwhelmed by the response from people donating in Claire's memory," she said.
"These donations will be put into a tribute fund and, following discussions with the family, will go towards projects they feel would have been important to Claire."
Devastated friends described Squires as a keen charity fundraiser who last month climbed Mount Kilimanjaro for the Royal Air Force Association
"Claire was larger than life, fun-loving, bubbly, happy, cheerful, kind, giving, thoughtful. She was just the most amazing person in the world - the best friend I have ever had," friend Victoria Hauser told 5 News.
"She was a giver, all the time. It's been never-ending. She's done the Great North Run, she's done a climb on Kilimanjaro, she's done a marathon previously for the Children's Society."
Around 37,500 runners took part in the marathon and Squires' death is the 10th since the race began in 1981. She is the only woman to have died in the marathon.
The most recent death was that of David Rogers, a 22-year-old fitness instructor, in 2007.