ATLANTA - A bomb rocked Centennial Olympic Park early Saturday, killing two people and injuring at least 110 revelers in the social center of the Olympic Games.
"We will consider it an act of terrorism until information should should arrive to the contrary," FBI Special Agent Woody Johnson said.
Johnson said a police officer had been called to an area of the park to deal with some unruly people. The officer spotted a suspicious package near an NBC stand and the area was evacuated, he said.
"Before they were able to clear people form the area, the device went off," he said.
Johnson said two people died and 110 injured.
Cameraman Mark Field of KNBC in Los Angeles said he was shooting footage near a four-story sound and light tower when he was told to evacuate about 1:15 a.m.
"A security guard tried to move us back because he said there was a suspicious package," Field said. "We got about 50 feet away and turned back. About five minutes later, we saw a large flash-bang. It did not seem like that large a bomb because the package was not that big, but pieces were flying everywhere."
Gary McConnell, director of the State Olympic Law Enforcement Command, told NBC that authorities were investigating the possibility of a pipe bomb.
CNN also reported that two explosive devices were later found in the park and police were sweeping the area with bomb-sniffing dogs.
Hospitals said they were treating some people who appeared to have been hit by shrapnel. A doctor said he saw a lot of fractures and one person with a finger blown off.
Snenetricus Warford said the explosion appeared to come from a garbage can. "I looked up, there was fire and smoke going up. People were there. It blew them over."
The explosion rocked buildings, shattering windows. It could be heard throughout the downtown area where tens of thousands of people have gathered every night since the Olympic Games began July 19. A Fire Department spokeswoman said at least 150 people were injured, but witnesses put the figure much lower.
R. Green, a morgue attendant at the Fulton County medical examiner's office, said he was told by the bomb squad that four people were killed.
"I felt the ground shake," said Desmond Edwards, an Atlanta schoolteacher. "Some people looked really messed up. There were rivers of blood."
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.
President Clinton, who has been in Atlanta twice during the Olympics, was awakened and told of the blast, Chief of Staff Leon Panetta told NBC.
The park is in the heart of downtown 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. There were at least 10 athletes from Cuba and Argentina a few feet away from the blast, said Sheryl Fillmore, a friend of a Cuban judo competitor.
There was no immediate indication of the cause of the blast. The last fatalities connected to an Olympic Games were the 11 Israeli athletes killed by terrorists at the Munich Games in 1972.
"It's horrible - the worst fears," said Bob Brennan, a spokesman for the Atlanta Committee for the Olympic Games.
Brennan said there were no plans to alter Saturday's schedule of sports events.
"Oh yes, I am assuming we can conduct the games," he said. "We don't know what happened, how it happened. So much speculation going on that it's difficult to know exactly what happened."
Witnesses said they people on the ground after the explosion.
"I thought it was fireworks, like a big boom, and I saw three guys laying in the street," said Terry Tyson. "They all had leg injuries. Blood was running down the street. It was horrible."
Police officer Ron Otero, who was patrolling in the park, said he was about 50 yards away when the tower exploded.
"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."
Emergency vehicles were lined up alongside the park. Police and other security officers swarmed through the streets trying to clear the area, forcing people away from the park which sits at the hub of the Olympic Games. Three major sports arenas are adjacent to the park, though sports competition had ended when the explosion occurred.
The tower, apparently used for lighting and sound near the main concert stage at the park, was still standing after the blast, but debris littered the base of the structure.
Centennial Olympic Park was opened just a week before the Olympics began, built on an area formerly occupied by vacant and decrepit buildings. The 21-acre park has sponsor buildings, concert stages and exhibits, and people were allowed to roam freely without the restrictions imposed on the Olympic sporting venues.