Some stored pyrotechnic materials have been discovered, he said in a late-night news conference, but gave no further details.
Twenty-five of the hospitalized victims were in critical condition.
The quick-moving fire in the small wooden structure was sparked by pyrotechnics used Thursday night by the rock band Great White, according to videotape shown repeatedly on television.
"If you weren't out of the building in 30 seconds, you didn't get out," the governor said he was told by survivors.
Authorities said they were investigating possible criminal charges as a result of the inferno.
Carcieri said 96 bodies were recovered, and that 187 people went to hospitals for treatment of injuries.
Adding in some 80 people who had escaped the fire and returned to the scene Friday to talk to authorities, there appeared to be more than 350 people inside at the time, the governor said, exceeding the premises maximum legal capacity of 300.
Many victims were severely burned or overcome by the thick, black smoke as they stampeded and jammed exits trying to escape from the popular concert hall.
"This shouldn't have happened," Carcieri said earlier after returning to the state from Florida and viewing the scene. "Somebody made a bad decision" in allowing pyrotechnics to be used in so small a building.
Jack Russell, the lead singer of the band Great White, told reporters he had permission from club managers to use pyrotechnics, but the owners denied permission had been asked for or granted.
"If we didn't (have permission) we wouldn't have even left the bus," Russell said. He said he understood that the club had a permit and had told his managers the band could use pyrotechnics.
The owners, Jeffrey and Michael Derderian, issued a statement Friday through their lawyer. It said: "At no time did either owner have prior knowledge that pyrotechnics were going to be used by the band Great White. No permission was ever requested by the band or its agents to use pyrotechnics at The Station, and no permission was even given."
Fire Chief Charles Hall said the town had no record of a permit for the use of pyrotechnics at the club. He said the building was totally engulfed in flames within three minutes.
"Nobody had a chance," Carcieri told reporters.
"We're all shocked, deeply, deeply saddened that something like this happened. It defies words. You cannot describe the sadness of something like this, the impact on families, and it didn't need to be," he said.
The governor said the "long process" of trying to identify the victims was under way.
Carcieri said authorities were putting the "highest priority" on identifying the individuals as rapidly as possible for the families impacted.
He said families would be notified as identities were confirmed.
Grieving relatives gathered at the nearby Crowne Plaza hotel as the process to identify the dead and injured got under way.
"This is a really tough, tough day," the governor said. He praised the "heroic efforts" of those who helped pull more than 100 people from the blazing building and rescue workers who searched the rubble for bodies in a "very agonizing, emotional and draining" effort.
Town Manager Wolfgang Bauer said the death toll, initially given as in the 20s, mounted through the day as firefighters found more bodies in the smoldering ashes.
Survivors told harrowing tales of horror and heroism.
"I saw people on the ground, getting stomped on, basically," said one young man who escaped. Another said people were jumping from the building, some in flames.
Witnesses spoke of how fast the fire spread and about people "scratching and clawing" to get out. People were panicked as they tried to get out the exits and windows.
Video showed people jammed up at the front door, screaming for help as black smoke billowed out behind them.
Others outside were pulling at outreaching arms, trying to help them escape. Some fled through windows. Many with burned hands stuck them into the snow.
The fire broke out during a pyrotechnic display at the start of the concert by the Great White, a rock band best known for its hit song "Once Bitten, Twice Shy."
Russell, helped to safety by security, said he couldn't believe how fast the hall went up in flames.
"This place went up like the Fourth of July," Russell said.
He said his guitar player, Ty Longley, was among the missing.
A WPRI-TV cameraman captured the scene inside as the band began its music set. The video showed sparks flying behind the band, igniting material on the side walls and quickly spreading to the ceiling as smoke began to fill the hall.
WPRI cameraman Brian Butler said some people yelled, "Yah! That's great!" when the fire began. "They thought it was part of the show," he said.
"A majority" of the dead were jammed at the front door, Hall said. "Stacked like cordwood," another fire official said.
Russell described the pyrotechnics as "sparklers," and that he'd never felt any heat from them during previous concerts.
Hall said there were no sprinklers in the building, but none were required because of the relatively small size of the structure.
Patron Linda Ormerod of Providence, R.I., saw the fire start and headed for the exit with her boyfriend.
"It was like a stampede. I really thought that was it for me. Everything went black," she said.
Someone "kicked out a window, I was hanging out the window, and then somebody threw me out," Ormerod said. "It was the most horrible thing I've ever been through.
"People were screaming, 'Help me, help me,' and I was screaming 'Help me' myself."
Another survivor said a "big man pulled me out. I owe him my life."
The injured were being treated at area hospitals for various degrees of burns and smoke inhalation. Eleven of the most seriously injured were flown to the Massachusetts General Hospital in Boston and the adjacent Shriner's Burn Center.
The fire broke out about 11 p.m. at The Station, a regular site for rock band appearances in the town near Providence. Thursday's concert was to feature Great White, a Los Angeles heavy metal/hard rock band that often uses "sparklers" in its act.
The fire was declared under control by 12:45 a.m. Friday.
Russell said he realized something was wrong when he felt heat on his back. When he saw the flames he assumed someone would come up on stage and put it out with a fire extinguisher, but no one did.
"I was trying to put it out with a bottle of water," Russell said. "I felt heat on my back. I turned around and the building was engulfed. My soundman is injured. I'm on my way to the hospital. I'm missing my guitar player."
"Rock and roll will never be the same for me again," Russell said.
Video of the incident showed the sparklers igniting the walls as Great White began its act. A stage technician told a local television station that soundproofing material caught fire.
The technician, Paul Vanner, told WPRI-TV the pyrotechnics "looked like a great effect, but it was way too much."
Vanner said that many local musicians were in attendance to see Great White. He said many people he personally knew were missing. Vanner, who worked for The Station for about three years, estimated that there were about 325 people in the club for the concert.
Hall said the facility had a maximum capacity limit of 300 for a concert, but said he believed there were fewer than that in attendance when the fire broke out.
Hall said there were four fire exits, but most patrons tried to get out the front.
The fact that many of those killed were found near a door was reminiscent of a melee Monday in a Chicago nightclub in which 21 people died. Most of those victims died as a crush of people tried to get out of the building after a security guard sprayed mace to try to break up a fight among several women.
The West Warwick fire is the worst in Rhode Island history terms of number killed. Ten women died in a Dec. 13, 1977, dormitory fire at Providence College.
It was the worst fire in the United States since more than 80 people died when federal authorities raided the Branch Davidian compound in Waco, Texas, on Feb. 28, 1993. The governor said the fire had become the fourth worst such fire in the nation's history.
The worst fatal nightclub fire in New England and the nation at the time was at the Coconut Grove in Boston on Nov. 28, 1942, when 492 people died.
"I'm not sure New England has seen anything like this since the Cocoanut Grove fire," said Dr. Joseph Amaral of the Rhode Island Hospital in Providence, where dozens of victims were taken.
(Reported by David D. Haskell in Boston and John Hendel in Washington)