Aerial view of the fire at a residential building in Nanjing city, Jiangsu province on February 23, 2024.
The building is located in the Yuhuatai district of Nanjing, a city of more than eight million that lies about 260 kilometres (162 miles) northwest of Shanghai.
By 6:00 am (2200 GMT Thursday), the fire had been extinguished, and a search and rescue operation ended around 02:00 pm Friday, authorities said.
Twenty-five fire trucks were mobilised to fight the blaze, emergency services said.
Footage circulating on Chinese social networks showed a skyscraper on fire in the middle of the night, with black smoke pouring from it.
Other images show gigantic flames consuming several floors of the building, the flashing lights of emergency vehicles visible nearby in the dark.
Additional footage, apparently taken later, shows white smoke pouring from several points in the building.
The 44 injured people were sent to hospital for treatment, officials said, adding one was in "critical condition" while another was seriously injured.
At a press conference, city mayor Chen Zhichang offered his condolences and apologies to the victims' families.
- Frequent fires -
Fires and other deadly accidents are common in China due to lax safety standards and poor enforcement.
And the country has seen a spate of deadly fires in recent months, often caused by official negligence -- prompting calls from President Xi Jinping last month for "deep reflection" and greater efforts to "curb the frequent occurrence of safety accidents".
In January, dozens died after a fire broke out at a store in the central city of Xinyu, with state news agency Xinhua reporting the blaze had been caused by the "illegal" use of fire by workers in the store's basement.
That fire came just days after a late-evening blaze at a school in central China's Henan province killed 13 schoolchildren as they slept in a dormitory.
A teacher at the school told state-run Hebei Daily that all the victims were from the same third-grade class of nine- and 10-year-olds.
Domestic media reports suggested the fire was caused by an electric heating device.
And in November, 26 people were killed and dozens sent to hospital after a fire at a coal company office in northern China's Shanxi province.
The month before, an explosion at a barbecue restaurant in the northwest of the country left 31 dead and prompted official pledges of a nationwide campaign to promote workplace safety.
And in April, a hospital fire in Beijing killed 29 people and forced desperate survivors to jump out of windows to escape.