ATLANTA -- Olympic officials Thursday agreed that Wednesday night's TWA explosion had cast a pall over the carefree festival planned for today's opening ceremonies here, but repeated their conviction that the Atlanta Games, which will run through Aug. 4, are secure.

Even if the crash was a result of terrorist activity -- a conclusion authorities have not drawn yet - International Olympic Committee (IOC) general director Francois Carrard said that local organizers, the city and the state "are doing a very good job" with security. "And we trust them."

The Atlanta Olympics is the largest, most expensive peacetime security operaton in American history and has a $303-million budget, $227 million of which will be paid for by the federal government. In addition, the Olympics has a security force of 30,000. That is three times the number of athletes, from 197 nations, who will participate in the Games.

"We have been told there was absolutely no connection between this awful tragedy and the Olympic Games," said Carrard, second-in-command at the IOC. "... We are confident that we are in the best absolute hands in regard to security."

IOC president Juan Antonio Samaranch sent a brief letter to President Bill Clinton expressing "deepest sympathy" to the "American people and the bereaved families," and Carrard echoed those remarks in an afternoon news conference.

"I'm sorry to say that Olympics, sadly, is accustomed to live in the world as it is," Carrard said. "That means, we live in a world where there are conflicts, dramas, accidents, terrorism here and there. But to relate both things is a total speculation."

Both the Atlanta Committee for the Olympic Games and Atlanta Police Chief Beverly Harvard issued statements saying they would continue to "monitor the situation." Harvard said security at Atlanta's Hartsfield Airport "has been enhanced for some time in preparation for the Summer Olympic Games." Clinton is due to arrive here at noon today to address the U.S. team. As head of state of the host nation. Clinton is scheduled to attend tonight's ceremonies and officially open the Games.

Atlanta has taken extraordinary security measures, including having frogmen patrol the waters of the Olympic rowing competition, welding shut of manhole covers throughout the city and using advanced technology such as the "hand geometry" identification system used to make credentials for athletes and VIPs. A Long Island company, Symbol Technologies Inc., has loaned 500 hand-geometry scanners to be used during the Games.

"We have taken an unbelievable number of precautions in planning for these Games," said Atlanta Mayor Bill Campbell, "so I have no doubt they will be safe. In fact, I believe Atlanta will be the safest place on the globe for the duration of the Games."

There was a report that a woman was allowed to enter Wednesday night's opening ceremonies rehearsal with a firearm in her purse. Officials, however, would not confirm it, Carrard said: "The fact that there are these reports is good. It means information is circulating and will be checked out. Nothing is perfect in the world. Perfect security could lead to freezing of movement."

Athletes Thursday said they felt safe. But some expressed anger at the possibility the Games would be used by terrorists for the world stage that the Olympics provides. "It's a shame that a few individuals in the world cause problems and disrupt the peace we're trying to have here," swimmer Jon Olsen said .

Since the 1972 Munich Olympics, when Palestinian terrorists murdered 11 members of the Israeli Olympic delegation, security at the Games has been intense and world events have added a sense of unease to the ever-growing Olympics. The last time the Olympics was staged in the United States, with the 1984 Los Angeles Games, there were Cold War concerns, even when the Soviets boycotted.

"It's really sad that sick, coward terrorists out there are forcing the biggest, best sporting event in the world to have more security than some wars," volleyball player Karch Kiraly said.

Mike Unger, Michael Dobie and Mark Herrmann contributed to this story.