Firefighters were called Tuesday to China's tallest building in Shanghai's financial center where smoke was billowing out of a high floor, police and witnesses said.
There were no immediate reports of casualties.
Thick smoke originated from a section of the main building of the International Financial Centre, about 40 floors above the ground.
The building is still under construction and is close to completion. Fire engines rushed to the scene and connected water hoses, while hundreds of onlookers gathered.
A member of the building's staff told Reuters that the fire was believed to have been caused by an elevator used by construction workers.
The fire was not large but strong winds were blowing out big quantities of smoke, he said.
The 400,000-square-metro IFC complex, being built by Hong Kong's Sun Hung Kai Properties, is to include two hotels and a shopping mall as well as top-grade office space, and to be completed by 2010.