The Metropolitan Police say they will be reviewing their security procedures following two explosions at the Boston Marathon in Massachusetts.
The blasts struck six days before thousands of athletes and fun-runners take part in the London Marathon.
Chief Superintendent Julia Pendry, the event commander, said security arrangements would be reviewed ahead of the event next Sunday.
She said: "A security plan is in place for the London Marathon. We will be reviewing our security arrangements in partnership with London Marathon."
Nick Bitel, the chief executive of London Marathon, said: "We are deeply saddened and shocked by the news from Boston.
"Our immediate thoughts are with the people there and their families. It is a very sad day for athletics and for our friends and colleagues in marathon running. Our security plan is developed jointly with the Metropolitan Police, and we were in contact with them as soon as we heard the news."
Over 50 of Jimmy Savile's sex abuse victims will seek compensation from the BBC, the NHS, the disgraced TV presenter's estate and other organisations, their lawyer has said. The scale of the late DJ's campaign of abuse was revealed in a report yesterday.
Savile now has 214 criminal offences, spanning the breadth of the UK, recorded against his name - including 34 rapes. The Department of Health (DoH) and BBC are among a number of organisations embroiled in the scandal and, alongside the late star's estate, could now face substantial payouts.
The DoH and BBC have launched internal investigations into how the entertainer slipped under the radar and was allowed to abuse on such an unprecedented scale.
The extraordinary extent of Jimmy Savile's double life as a predatory paedophile has been laid out in black and white today. His youngest victim was an 8 year old boy, he assaulted a teenager in a Yorkshire hospice and his abusing lasted 54 years.
The first report into his decades of abuse was made public with the senior Scotland Yard detective admitting that Savile conned millions and had in fact "groomed the nation".
An alleged victim of Savile says she was told by police in 2008 that she risked being branded a 'liar', while his lawyers 'made mincemeat of her'.
Because he had plenty of money, Jimmy Savile would have the best lawyers, it would all take place in a big court in London and his lawyers would make mincemeat of her. She also got the clear impression from the police that she would be publicly branded a liar and that her name would be all over the newspapers, particularly if she lost the case.
An allegation also emerged today that Jimmy Savile sexually touched a girl aged between 13 and 16 at the final regular recording of 'Top Of The Pops' at Television Centre in 2006.
Speaking to our UK Editor Lucy Manning, Met Commander Peter Spindler said he hoped today's reports would help give victims a voice and sense of justice.
The BBC today said it was "appalled" that some of the offences by Jimmy Savile "were committed on its premises", adding that it "would like to restate our sincere apology to the victims of these crimes".
The Prime Minister's view of this is that it is absolutely right that every institution involved gets to the bottom of what has gone on.