CHONGQING, Jan. 2 (Xinhua) -- An initial investigation showed that a building fire in southwest China's Chongqing Municipality was caused by a balcony fire, local authorities said Thursday.

The fire broke out around 5 p.m. Wednesday in a residential building in Yubei district, and no casualties were reported, according to the district's fire brigade.

Preliminary investigation showed the fire started from a balcony on the second floor of the 30-story building, and ignited the building's insulating layer and rain sheds.

The specific reason for the fire is still being investigated.