A fire at a nursing home in northern China has killed 20 people, according to state media, as officials investigate the cause of the fire.

China’s official Xinhua news agency said Wednesday 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.

In January, a fire at a food market in the Hebei city of Zhangjiakou killed eight people and injured 15 others.