Although the motive for yesterday's bombings in London is not clear, one thing is: The financial and emotional repercussions are likely to be felt by every city that has been awarded the Olympics.
The attack on London, the winner of the 2012 Summer Games, turned jubilation into shock and sorrow. It also brought a quick response from the International Olympic Committee.
"It wasn't an attack against the Games," IOC President Jacques Rogge said. "Cities like London, Paris, New York all face these kind of risks, and remember what happened in Moscow and Madrid. There are no safe havens."
IOC spokeswoman Giselle Davies stressed that the decision to award the games to London was not in jeopardy. London narrowly beat Paris in voting Wednesday.
"We have full confidence in the London authorities in securing the event," Davies said in Singapore, where the IOC is meeting.
Security for last year's Athens Games, which came just four months after the bombings of Madrid trains, cost a record $1.5 billion and involved the world's intelligence and military might.
These attacks will most certainly add to the security bill, starting with next year's Winter Games in Turin, Italy.
"For Torino, it's a wake-up call," said John Bevilaqua, a sports marketing consultant who was in charge of communications at the 1984 Summer Games. "China has virtually locked down its country, but for Vancouver [in 2010] and now London, it means a renewed commitment to security. They simply cannot allow anything to happen."
London Olympic organizers shelved plans for a celebration yesterday.
"It's terribly unfortunate in terms of timing," said Keith Mills, chief executive of London's bid team. "Our thoughts go out to the families who've been affected. I hope that the security forces can get to the bottom of this quickly."
But shocked residents worried about what the future might hold.
"Yesterday, we were quite glad that we got the Olympic bid," said Arvind Mavji, a worker at Euston railway station. "Today, we are wondering if it was worth it."
That attitude might change, if the first Olympics after the Sept. 11 attacks were an indication, said Lisa Delpy Neirotti, associate professor of tourism and sport management at George Washington University.
"Terrorists put a damper on the celebration, but the bombings are going to make people support the 2012 Olympics even more," she said. "The 2002 Winter Games were right after a far worse incident, and people rallied and had fun. There is a `the Games must go on' philosophy that started with Munich in 1972 and continues to this day. Greece had bombings almost right up to the opening ceremony. It could have happened in any one of the [bid] cities. It happened in Madrid."
Before the Athens Games, security experts predicted that terrorists would pass up the virtual fortress the Olympics have become in favor of soft targets with fewer safeguards.
The "arms race" between security experts and terrorists is likely to continue unabated, said Bevilaqua. For example, his company, Sequiam Sports, devised an ID card with a thumbprint scan that was tested at an Olympic-related event in Athens.
"As terrorism has grown, so has the ability to deal with it," he said. "The high-water mark for security was Athens. That mark will be exceeded. They're going to spend whatever it takes.
The Associated Press contributed to this article.