Smoke and flames are seen engulfing a 20-storey office building in Zhengzhou, Henan province, China February 1, 2018. REUTERS/Stringer

BEIJING (Reuters) - A blaze raged through a 20-storey office block in Zhengzhou, capital of China’s central province of Henan, on Thursday, sending heavy smoke into the sky, but no one was believed to have been killed.

Smoke and flames engulfed the entire eastern side of the building after the blaze broke out among insulation materials on an upper floor, according to state broadcaster CCTV.

The fire was brought under control in the afternoon and firefighters had not found any casualties, the Zhengzhou fire department said on its official social media account.

The cause of the fire was under investigation.