SECURITY arrangements for the London Marathon will be reviewed after explosions ripped through the finish line of the Boston Marathon yesterday (April 16).

There are just six days after thousands of athletes and fun-runners are set to cross the start line in Blackheath for the 26.2 mile London race and the organisers say it is expected to go ahead as scheduled.

In a statement the organisers said: “We are deeply saddened and shocked by the news from Boston.

“Our immediate thoughts are with all the people there and their families. “It is a very sad day for athletics and for our friends and colleagues in marathon running.

“We fully expect that Sunday’s race, registration and associated events will go ahead as originally scheduled.

“We are currently reviewing all our security arrangements with the Metropolitan Police and we will post the latest information on all the events through Twitter, Facebook, emails and our website.”

Hundreds of British runners lined up for the race in Boston yesterday and it is feared some of them may be among those injured.

Television pictures showed bloodied spectators and runners lying on the ground, emergency workers ripping away fencing and others carrying injured men and women from the scene.

Pictures also emerged on Twitter showing casualties lying on the pavement on Boylston Street - the main road through the east coast city - and debris blowing around them. Another photograph appeared to show participants running down the street at the moment an explosion created a fireball, sending smoke into the air.

A Foreign Office spokesman said: "We are aware of the incident and we are trying to gather information." Foreign Secretary William Hague tweeted: "Appalled by news of explosion at Boston marathon. My thoughts are with everyone affected by it and all those waiting for news."

Prime Minister David Cameron wrote on Twitter: "The scenes from Boston are shocking and horrific - my thoughts are with all those who have been affected."

And the Met’s event commander for the London Marathon, Chief Superintendent Julia Pendry, said security arrangements will be reviewed following the explosions in Massachusetts. She said: "A security plan is in place for the London Marathon. We will be reviewing our security arrangements in partnership with London Marathon."

Labour leader Ed Miliband wrote on Twitter: "Appalling news from Boston. All of my thoughts are with the casualties and their families."

Security for the London Marathon and Baroness Thatcher's funeral will be under scrutiny in the aftermath of the devastating blasts. The Met Police said they would review the policing of the race on Sunday, while former Home Secretary John Reid said the incident will also have ramifications for Lady Thatcher's funeral on Wednesday.