Tests to establish how a 30-year-old runner collapsed and died as she neared the finish line at this year's London Marathon are expected to take place in the coming days.
The woman, who is yet to be formally identified, fell to the floor as she made her way along Birdcage Walk, near St James' Park, on the final stretch of the 26.2 mile course, the event's organisers said.
She was given medical attention by paramedics but died at the scene yesterday afternoon.
A statement on the London Marathon website said: "We would like to emphasise that our immediate concern is for the family of the deceased. Our thoughts and deepest sympathies are with them at this difficult time."
The statement added: "We will not be releasing any further details of this tragic incident until next of kin have been notified and formal identification has taken place. We would ask for your understanding in this matter."
The fatality occurred with the finishing line only one bend away.
Birdcage Walk borders St James's Park and is the last road that runners have to travel before reaching Buckingham Palace where they turn onto The Mall on which the finish line is located.
Competitors do not reach Birdcage Walk until after completing 25 miles of the marathon.
The tragic death was the 10th since the London Marathon began in 1981.
Five of the previous fatalities were a result of heart disease in runners apparently unaware that they had a problem. Four of these were cases of severe coronary heart disease.
The last competitor to die was a 22-year-old fitness instructor in 2007.
Prince Harry was among the cheering crowds as tens of thousands of fun runners and amateur athletes completed the 32nd London Marathon.
Up to 37,500 runners set off through the streets of the capital to earn their medals and raise money for countless charities.
Runners were given a Royal welcome as the Prince offered support to those crossing the finish line.
He joked that the Duke and Duchess of Cambridge planned to run the 26.2 mile course next year, as he met volunteers and presented prizes to the winning athletes.
In the elite races, the event was dominated by the Kenyans, with Wilson Kipsang winning the men's race at his first attempt with a time of two hours four minutes and 44 seconds.
Compatriot Mary Keitany retained her London Marathon title with a time of two hours 18 minutes and 36 seconds, setting a new national record in the process.
Britain enjoyed a double victory in the wheelchair races, with wins for David Weir and Shelly Woods.
Claire Hallissey won the shoot-out between hopefuls for the final place on the British Olympic women's marathon team.
As well as the professional athletes, an eclectic group of fun runners set 29 marathon world records.
Some 107 runners competed to break 55 world records, including David Stone who set a new Guinness World record for the fastest marathon dressed as a book character.
The 42-year-old from Exmouth, Devon, completed his run in two hours 42 minutes dressed as Count Dracula, having donned a Superman outfit last year to break the record for fastest marathon dressed as a superhero.
A host of famous faces also took part in this year's run in support of good causes.
The fastest female celebrity was Nell McAndrew, who broke down in tears after breaking the three hour mark, finishing with six minutes to spare.
Rower James Cracknell was the only other celebrity to finish in less than three hours, crossing the line in two hours 59 minutes having recently recovered from a life-threatening head injury.
Newsreader Sophie Raworth, who collapsed at the 23-mile mark in 2011, banished the memories of last year's marathon to finish the race in three hours 56 minutes.
Shadow Chancellor Ed Balls clocked a time of five hours and 33 minutes and revealed he would be celebrating with a well earned bitter.
He said: "As you will know I didn't quite drop pasties from my training diet but I've had an abstentious week or so I think I might have a pint of bitter."
Balls said his marathon run had raised £56,000 so far for the charities Whizzkids and for Action for Stammering Children.