Claire Squires, a London Marathon runner who suddenly collapsed and died near the end of the race on Sunday, has inspired an outpouring of charitable donations that have now surpassed £600,000, which amounts to nearly $1 million USD.

Squires, 30, was a hairdresser from North Kilworth in England. She was running in the 2012 London Marathon to raise money for an organization called Samaritans, which provides confidential support for distressed people in order to prevent suicide.

She collapsed near Buckingham Palace, less than a mile from the finish line. Medics arrived to assist her immediately, but no one could revive Squires. The exact cause of death for this healthy and experienced long-distance runner is still unknown.

Claire Squires' boyfriend, a property developer named Simon Van Herrewege, 31, told the London Evening Standard that Squires was an incredible person. She was happy-go-lucky and so driven. She had a heart of gold. I love her more than words can say and she will be dearly missed, he said.

Claire is survived by her mother, father and three sisters. The family released a statement about the tragedy. We are all devastated. It's a total shock because she was such a fit girl. We've no idea what caused her death, it read.

Claire has raised thousands of pounds over the years for charities. If any more money can be raised that would be fantastic.

Squires' story is the tale of a young woman rising gracefully to the challenges of tragedy and adversity. Her family's trials began when Claire's brother Grant, 25, saw his girlfriend Heidi Richardson killed in a car crash in 2001. A week later, Grant fatally overdosed on heroin and other drugs.

After her brother's death, Claire Squires committed herself to charitable causes. She completed the Great North Run to raise money for The Children's Society, and she even climbed Mount Kilimanjaro last year with a friend to support the Royal Air Force Association.

Claire's mother Cilla got involved with Samaritans as a volunteer 24 years ago. For decades she has manned the phones there, hoping to prevent tragedies like the one that eventually claimed her son.

Now her daughter has died too. But since Claire had been working to support Samaritans during her final moments on earth, public support for the charity on her behalf has been monumental.

The volunteers at Samaritans now have increased capabilities to reach out and help even more people. Such a compassionate public response to the death of Claire Squires may very well save countless lives.

Anyone interested in donating to the cause can visit Claire Squires' fundraising site on JustGiving, by clicking here