A three-alarm fire broke out Friday on the roof of the Monte Carlo hotel-casino on the Las Vegas Strip and spread rapidly, but was contained within about an hour.

"We have knock down," Clark County Fire Chief Steve Smith said.

• Click here to view photos.

Smith couldn't estimate damage to the 32-story hotel.

"As we go out of the danger zone, we'll methodically check each floor," said the chief. "No rooms are burning."

The fire broke out about 11 a.m. local time and spread from the center section of the hotel across the roof line. The top four or five floors of the building were engulfed in flames, but firefighters contained most of the blaze by shortly after noon, according to the Clark County Fire Department.

• FOX Facts: 1980 Fire at MGM

Fire officials said no one had been trapped by the flames, despite initial reports indicating that four workers were, according to Clark County spokesman Eric Pappa.

An ambulance company spokeswoman said 17 people were taken to area hospitals with minor injuries, mostly from inhaling smoke or from fleeing the building. None of the 120 firefighters who fought the blaze was hurt.

Orange flames licked at the hotel's sign and plumes of thick black smoke poured from the rooftop of the resort. Embers fell to the street below.

• Fast Facts: Monte Carlo Hotel-Casino

The cause of the blaze wasn't immediately known, but Pappa said county officials were told that there were welders working on the roof before the fire broke out.

There was no immediate indication of criminal activity or arson, the fire chief said.

Smith called it an external fire, but said heat and smoke set off alarms and sprinklers inside the building.

The facade was made of a foam construction material that "melted off the side of the building and started a few fires below," Smith said.

People were reportedly evacuated from the Monte Carlo, and new guests were turned away while firefighters struggled to extinguish the flames.

Floors 25 to 32 were immediately evacuated, and lower parts of the hotel were still being cleared about 90 minutes later.

"The building is being evacuated," said Gordon Absher, spokesman for the hotel owner, MGM Mirage Inc. "We've gone door to door evacuating the hotel. The casino is closed and secured."

The Bellagio and New York-New York casinos had been prepared to evacuate if necessary.

Click here for video.

Larry Wappel, 25, of San Pierre, Ind., said he and his brother, Eric Wappel, were in a room on the 30th floor when they heard housekeeping staff banging on doors and yelling "Fire, get out!"

He said it took about 10 minutes to walk single-file down the stairs to get to ground level.

Wappel said there was no panic.

"There were a couple of ladies crying, but it was pretty calm," he said.

Another guest, Renza Badilla, 45, said she exited through the hotel kitchen to find burning debris and embers falling from the roof.

"I think people were shocked when they saw the smoke," said Badilla, who said she was in the buffet on the main casino level when fire alarms sounded. "We thought the fire alarms were just drills. But the wait staff and kitchen staff were really helpful getting us out through the kitchen."

Guests were taken the MGM Grand Garden Arena and employees were evacuated to the adjacent New York-New York hotel, Absher said.

City and county firefighters were all on the scene battling the blaze, according to Las Vegas fire spokesman Tim Szymanski.

Smith said the fire was fought inside the building by about 100 firefighters, not with ladder trucks.

Huge crowds formed to watch the fire, and traffic on the Las Vegas Strip was gridlocked as streets were blocked off around the hotel. Helicopters circled overhead.

One witness reported more than 20 fire and rescue trucks were on the scene along with several ambulances.

"There is an incredible amount of thick smoke," Robin Leach told FOX News. "A lot of the strip is shut down."

The nearby resorts, Bellagio and New York-New York, were not evacuated.

The Monte Carlo Resort & Casino has 3,002 guest rooms and 211 suites. The resort, located on Las Vegas Boulevard, near Tropicana Avenue, opened in June 1996.

The 32-story casino-hotel modeled after the Place du Casino in Monte Carlo, Monaco, was a joint venture between Steve Wynn's Mirage Resorts and Circus Circus Enterprises.

It is now owned by MGM Mirage Inc. and is planned to be linked by a monorail that will connect it to the CityCenter casino complex and Bellagio to the north.

Click here to read more on this story from the Las Vegas Review-Journal.

The Associated Press contributed to this report.