LAS VEGAS (Reuters) - Fire forced guests and staff to evacuate the 3,000-room Monte Carlo Resort & Casino in Las Vegas on Friday, quickly engulfing parts of the upper floors, facade and roof before being brought under control.

There were no serious injuries in the blaze, first reported at about 11 a.m. (2 p.m. EST) in the south tower of the huge hotel complex on the Vegas strip, but a dozen people were treated for smoke inhalation, authorities said.

The Monte Carlo -- owned by MGM Mirage, the world’s second-largest casino operator -- was quickly evacuated and the strip was shut down in both directions, jamming traffic back onto Interstate-15 as embers and debris fell into the street.

Television images showed flames sweeping across the 35-story hotel’s white and black facade, with dark smoke belching into the sky as fire crews scaled ladders.

The blaze was contained and largely extinguished in about an hour but authorities said the hotel and casino would remain closed until they were fully inspected.

Local media reports said the fire may have started on the hotel’s roof, where welders were working, but authorities said the cause had not been determined and was under investigation.

The fire burned “just on the upper couple of floors” and the damage may be just to the exterior of the building, said Gordon Absher, a spokesman for MGM Mirage.

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“We’ve been going door to door. All of our emergency procedures are working,” Absher said of the evacuation, adding that some guests were being relocated to other MGM properties in the area, including the New York-New York and MGM Grand.

A fire in November 1980 at one of MGM’s more famous properties, the MGM Grand, claimed more than 80 lives and injured nearly 700 people.

MGM owns several luxury hotels in Las Vegas, including the Bellagio.

The Monte Carlo, which opened in 1996, was built at a cost of more than $300 million and modeled after the Place du Casino in Monte Carlo.

Amenities include a grand lobby, spa and fitness facilities, shopping mall and 21,000-square-foot (1,950-square-metre) pool area with a tropical theme.