BEIJING -- Twenty-one people have died in a fire at a Beijing hospital that forced the evacuation of dozens of patients, Chinese state media reported.

Staff removed 71 patients after the fire broke out Tuesday in the inpatient department of Beijing Changfeng Hospital, state media including CGTN reported.

Videos of the fire circulating on social media show black smoke billowing from the building, with some people climbing out of the windows using what appears to be makeshift ropes made out of bedsheets. Others took refuge on air conditioning units outside the windows.

State media said the fire has been extinguished and rescue work has been completed.

The cause of the fire is under investigation, the reports said.