London, England (My Sportsbook) - Just one day after London was awarded the 2012 Summer Olympics, the city was working to recover from fatal blasts that caused the deaths of 37 people and wounded at least 700 more.

Three blasts took place in the city's subway system and one more rocked a double-decker bus in the worst attack on London since World War II.

A group called the "Secret Organization - al-Qaida in Europe" released a statement on a website Thursday claiming responsibility for the bombings.

Less than 24 hours before that, London was celebrating its surprising upset over European rival Paris to win the 2012 Summer Games. However, on Thursday, the thoughts turned to sadness and anger.

"The entire London 2012 team are shocked and deeply saddened by today's tragic events in London," said London 2012 Chairman and two-time Olympic gold medalist Sebastian Coe and Chief Executive Officer Keith Mills in a joint statement. "Our thoughts are with the families of the bereaved and all those who have been injured in these despicable terrorist attacks."

International Olympic Committee president Jacques Rogge also expressed his sympathy after writing to British Prime Minister, Tony Blair, and to the Mayor of London, Ken Livingstone.

"It is a very sad fact of society today that tragic and shocking attacks of this nature can happen in any city at any time," Rogge said. "The IOC's thoughts are with all those who are personally affected."

Livingstone called Wednesday's moment of Olympic bliss "amazing," but a day later was trying to encourage Londoners to support each other.

"Innocent people from all of London's communities have been targeted by this indiscriminate attack," Livingstone said. "I urge Londoners from all of this city's diverse communities and faiths to support one another and stand together against terrorism."

President George W. Bush released a statement shortly after the blasts from Scotland, the day in which the G-8 summit of the world's most powerful leaders was starting.

"I spent some time recently with the Prime Minister, Tony Blair, and had an opportunity to express our heartfelt condolences to the people of London, people who lost lives," the President said. "I appreciate Prime Minister Blair's steadfast determination and his strength."

In the United States, Homeland Security Secretary Michael Chertoff raised the terror alert level from yellow to orange, indicting high risk of terrorist attacks for mass transit.

Security was increased and there was a moment of silence after the sixth inning of the game between the New York Mets and Washington Nationals at RFK Stadium.

The British Open, golf's third major tournament of the year, is expected to go on as planned next week at St. Andrews in Scotland.