BEIJING (Reuters) -Sixteen people were killed in a fire at a department store in Sichuan province in China's southwest on Wednesday evening, state media said on Thursday.

The fire broke out in a 14-storey building in a high-tech zone of the city of Zigong, shrouding the vicinity with thick smoke, according to the Xinhua news agency.

Overnight rescue work ended at 3:00 a.m. (1900 GMT on Wednesday), state broadcaster CCTV said.

Preliminary investigation showed the fire was due to construction operations. Further investigation was underway to identify the specific cause of the fire.

(Reporting by Urvi Dugar in Bengaluru and Liz Lee in Beijing; Editing by Hugh Lawson and Tom Hogue)