China state media has reported of a fire outbreak in the northern part of the country, killing 20 people.

On Wednesday, China’s official Xinhua news agency said the fire started at 9 p.m. local time (9 a.m. ET) Tuesday in Chengde city in Hebei province. Six hours later, 20 people were confirmed dead.

State broadcaster CCTV said 19 others, who were uninjured, have been transferred to a hospital for observation.

Officials are investigating the cause of the fire. State media said a “relevant” person in charge of the facility has been taken in by police, without giving any details.