A blast hitS an office building in Xi'an, capital city of Northwest China's Shaanxi province, on Wednesday afternoon. [Photo/CFP]

XI'AN - A blast hit an office building in Xi'an, capital city of Northwest China's Shaanxi province, on Wednesday afternoon. Casualties are not yet known.

The blast occurred around 5 pm within a film animation industrial park in Beilin District, sources with the city's fire fighting authorities said.

Part of the building's walls have collapsed, according to the sources.