ATLANTA (AP) _ Terrorism struck the Olympics for the first time since Munich in 1972 as a pipe bomb exploded today in the heart of the Summer Games, killing at least one, wounding more than 100 and jolting thousands crowded into Centennial Olympic Park.

A caller to 911 about 18 minutes before the explosion warned of a bomb. The call came too close to the time of the blast to alert police at the park, though officers there already had begun clearing the area after finding a suspicious package.

President Clinton called the attack ``an evil act of terror'' and ``an act of cowardice that stands in sharp contrast to the courage of the Olympic athletes.''

Clinton, who attended the games with his family earlier, said new measures would be added to a security effort he called the most extensive ever for an Olympics.

As in Munich, when the Olympics continued even after terrorists killed 11 Israeli athletes and coaches, officials in Atlanta said they would not halt the games.

``The games will go on,'' said Francois Carrard, director general of the International Olympic Committee.

And so they did, beginning with a moment of silence and the lowering of flags to half-staff at all venues on the day of the games' glamour event: the 100-meter dash.

At Lake Lanier, site of today's rowing finals, soldiers carrying machine guns patrolled the grounds. Soldiers _ rather than the usual Olympic security _ manned the security checkpoints. Athletes as well as spectators were searched thoroughly.

The bomb went off at about 1:25 a.m. as thousands of revelers were celebrating at an open-air rock concert in the park. That was about an hour after the end of the Dream Team's game at the nearby Georgia Dome.

The park can hold 50,000 and Atlanta Police Chief Beverly Harvard said it was crowded when the bomb went off.

The explosion could have been much deadlier had police not quickly cleared the area after finding what they believed was a suspicious package.

No American athletes were injured, U.S. Olympic Committee spokesman Mike Moran said. There were no immediate reports of athletes from other countries injured.

``I feel bad for the people who were killed, and I feel bad for the people who were injured,'' said Charles Barkley, who is staying with other Dream Team players at a hotel about a block from the blast.

``It's something we thought about coming into the Olympics, but it's not something we thought would happen. I just feel bad for all the families involved.''

Barkley fully supported the plan to move on with the games.

``To let whoever did this get away with this and cancel the games, that would be absurd,'' he said.

The 21-acre Centennial Olympic Park is in the center of downtown Atlanta, within walking distance of three major Olympic venues. While people pass through metal detectors at all Olympic venues, anyone is free to walk through the park.

Billy Payne, president of the Atlanta Committee for the Olympic Games, said no one had ever recommended to him that security for the park be tightened.

``People have to have some freedom of movement,'' he said this morning on NBC's ``Today'' show.

Mayor Bill Campbell praised police for reacting quickly before the explosion.

``The security knew it was a problem, and they evacuated the area, avoiding a tragedy of epic proportions,'' Campbell said.

``The ultimate message we must send is that you can't be beaten by terrorism. It's a bad day for Atlanta, it's a bad day for the Olympic Games and it's a bad day for the country.''

FBI Special Agent Woody Johnson said two people died. But one, Turkish Radio and Television cameraman Melih Uzunyol, died of a heart attack while running to film the explosion's aftermath, TRT said.

WSB-TV quoted journalist Zafer Akyol, a friend of Uzunyol, as saying Uzunyol had a history of heart problems.

A woman was the other fatality. Her name wasn't immediately released.

Johnson said 111 people were injured, including 11 who required hospitalization. All of those hospitalized were in stable condition, he said.

Among those injured were six State Patrol agents and one Georgia Bureau of Investigation officer, said Sid Miles, commissioner of the Georgia Department of Public Safety.

Witness Desmond Edwards, an Atlanta school teacher, said the ground shook when the bomb exploded.

``Some people looked really messed up. There were rivers of blood,'' Edwards said.

``I thought it was fireworks, like a big boom, and I saw three guys laying in the street,'' said witness Terry Tyson. ``They all had leg injuries. Blood was running down the street. It was horrible.''

Justice Department spokeswoman Carole Florman in Washington said the FBI confirmed that the explosion was caused by a pipe bomb.

Florman said there were a number of calls after the blast alerting authorities to abandoned or suspicious parcels. Since the games' opening ceremonies July 19, about 120 packages were checked and no explosives found, she said.

The police officers who began clearing the scene shortly before the blast were reacting to an unattended satchel, which looked like a gym bag or knapsack, according to a Justice Department official who requested anonymity. That bag contained the pipe bomb that exploded.

Police bomb squad officers saw three pipes, but they may all have been part of one bomb rather than three separate ones, said a law enforcement official requesting anonymity.

The bomb detonated after authorities began evacuating the area where the package was found, the FBI's Johnson said.

The Justice Department official said the 911 call came from a pay telephone about two blocks from the explosion. The caller spoke ``in a calm voice,'' the official said.

The call, apparently from a man, was received at 1:07 a.m. and the caller said only that a bomb would explode in Centennial Park in 30 minutes, a law enforcement official said.

The caller did not give a name or identify any group or organization claiming responsibility for the bombing.

Johnson said authorities believe the caller was ``a white male with an indistinguishable accent.'' He refused to say if the caller said why the bomb had been planted.

Investigators at the scene have found nails and screws that were part of the bomb, a federal law enforcement official said. The official said the nails and screws probably were placed there to produce shrapnel to harm people.

At Hartsfield Atlanta International Airport this morning, spokeswoman April Majors said the airport is increasing its already high security because of the explosion.

For example, she said, airport security will conduct ``constant, random checks of trash receptacles.'' She would not detail other measures.

Johnson of the FBI said security forces would thoroughly search every Olympic venue before events at those sites resume. ``All of the venues will be sanitized again,'' he said.

Officials had hoped to re-open Centennial Olympic Park today. But Johnson later said it would remain closed indefinitely.

At the time of the blast, the band Jack Mack and the Heart Attack was playing a free concert on the park's main stage.

Mark Smith, who was mixing the music for the concert in a tower near the explosion, said he was a few yards from a police officer injured when the bomb went off.

``I saw the cop right in front of me take a huge piece of shrapnel,'' Smith said. ``He got hit bad. I saw 10 pockets of people hit by what appears to be shrapnel.''

Buddy Nix, head of the Georgia Bureau of Investigation, said GBI officer Tom Davis of Milledgeville, Ga., first noticed the suspicious bag.

Campbell, the Atlanta mayor, said Davis spotted the sack next to the sound mixing tower for the concert and found the bomb inside. Three or four people were sitting right next to the sack, Campbell said.

``As he was moving crowds away from the bomb, it detonated and he was thrown to the ground,'' the mayor said.

After the explosion, police swept the area with bomb-sniffing dogs and blocked off all surrounding streets. Dozens of ambulances, fire trucks and police cars lined up to care for the injured and keep out everyone else.

At least 10 athletes from Cuba and Argentina stood a few feet away from the blast, said Sheryl Fillmore, a friend of a Cuban judo competitor.

Most competitors have been living in the athletes village about a mile from the bombing.

``Our athletes in the village and elsewhere are planning to go forward in the competitions, yes,'' the USOC's Moran said. ``Obviously, there's been a heightened security activity, especially in the athletes in village.

``The athletes in the village all were up and watching on television at one time or another. Word spread fairly quickly.''

Eight officers with the State Olympic Law Enforcement Command were among those injured, said SOLEC spokeswoman Bill Wells. SOLEC is in charge of organizing 4,500 state law enforcement officials who run security at some 23 state-owned venues.

The eight were trying to move people away from the suspicious package. All were treated at hospitals and released.

The explosion rocked buildings more than a quarter-mile away, shattered windows in the immediate vicinity and could be heard throughout the downtown area, where tens of thousands of people have gathered every night since the Olympic Games began July 19.

Police officer Ron Otero, who was patrolling in the park, said he was about 50 yards away when the blast hit.

``I saw lots of smoke and heard a big explosion, very big _ it was like a shock wave hit us,'' Otero said. ``The next thing you saw was people on the ground.''

Police cordoned off the area for several blocks around where the explosion occurred, forming lines by interlocking arms and driving back tourists and journalists. They said the security net was to protect bystanders from further explosions.

Officials with the organization committee for the 2000 Sydney Olympics said they spoke this morning with Atlanta Olympics organizers and supported the decision that the games would continue.

Mal Hemmerling, the Sydney group's chief executive, said his group will review security implications of the Atlanta explosion after returning to Australia.

To Matt Ghaffari, an American silver medalist in Greco-Roman wrestling, the Atlanta Games are now ``the tainted games.''

``I want to go to the hospital and take my medal and some pins to make people happy,'' Ghaffari said. ``I can't tell you how sad I am. I'm ashamed as a person, as a human being. I would like to kick the guy's butt who did this.

``Now, when people say 1996, they're not going to remember the medals we won. They're going to remember this is the place where they had the terrorist attack.''

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EDITOR'S NOTE _ Associated Press Writer Michael J. Sniffen in Washington contributed to this story.