Race organisers of the London Marathon which involves around 36,000 runners, were quick to react on Monday night to the reports from Boston, immediately beginning a dialogue with the Met.
Speaking to BBC Radio 5 Live, Nick Bitel, chief executive for the London Marathon, said: “We will not be cancelling, what we are doing, we are reviewing.
“You look at what has occurred, if there are steps we can take to increase security and all sorts of measures one could deploy.
“We run through the city, when you have an event of any nature, a marathon, parade, it’s only as safe as the city itself, if it’s not held in a stadium you can’t do a lockdown like you may do in a building.”
In an earlier statement, Bitel 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.”
Met Police Chief Superintendent Julia Pendry said: “A security plan is in place for the London Marathon. We will be reviewing our security arrangements in partnership with London Marathon.”