A fire killed at least 21 people at a hospital in Beijing today and forced dozens of people to evacuate, Chinese state media reported.

As clouds of black smoke billowed into the sky, people trapped in the multi-storey building apparently tied bed sheets into makeshift ropes and escaped by climbing out windows, as seen in videos circulating on social media. Others took refuge by perching on air conditioning units just outside.

Emergency crews have since extinguished the fire, which broke out in the east wing of the inpatient department of Beijing Changfeng Hospital, state media including CGTN reported, and at least 71 patients were rescued. The cause of the fire is under investigation.

Most of the hospital building appeared to be without power late on Tuesday, with only a few windows illuminated by the flickering flashlights of workers inside. The exterior of the building was blackened and charred in places, and police cars could be seen parked at the north entrance.

There was no official word on how many of the dead were patients or the number of people who may have been injured.