Welders' sparks were blamed for igniting a large block of insulation at a casino construction site Wednesday.
The fire sent dark smoke billowing over the Strip and sparked a brief two-alarm call for firefighters to respond to the high-rise Fontainebleu-Las Vegas building site, a fire official said.
No injuries were reported after the 2 p.m. fire, which was quickly doused and did not damage the building, fire spokesman Scott Allison said.
"Lots of smoke. Impressive looking. But not a lot of fire."
Nevada state Occupational Safety and Health Administration and Clark County fire investigators were probing the fire, which Allison said burned part of a block of plastic and rubberized insulation material about the size of a tractor-trailer.
The $2.8 billion Fontainebleau is due to open in late 2009 with almost 4,000 hotel rooms, condominiums, a casino and spa.