Fifteen people have been killed and more than 40 injured after a fire ripped through an apartment building in eastern China, local authorities said.

Footage shared on social media showed flames and plumes of black smoke engulfing several floors of a skyscraper in Nanjing city.

Officials suggested the blaze started on the first floor of the building, where electric bikes were being stored.

But the specific cause of the fire remained under investigation.

The building is located in the Yuhuatai district of Nanjing, a city of more than eight million that lies about 162 miles (260km) north-west of Shanghai.

Emergency service crews were first alerted to the blaze at 04:40 local time (20:40 GMT) on Friday, officials said on Saturday morning.

Twenty-five fire engines and 130 firefighters were sent to tackle to the blaze. By 06:00 (22:00 GMT), the fire had been extinguished, with the search and rescue operation ending around 14:00.

Of the 44 injured people sent to hospital for treatment, one is in critical condition and another seriously injured, the officials said.

At a press conference, Nanjing Mayor Chen Zhichang offered his condolences and apologies to the victims' families.

Aerial photos of the skyscraper shared on Friday after the fire had been extinguished showed some flats up the length of the building with blackened fronts.

Fires and other deadly accidents often occur in China due to lax enforcement of safety standards.

A recent spate of deadly fires across the country prompted President Xi Jinping to call last month for "deep reflection" and greater efforts to "curb the frequent occurrence of safety accidents".

The Nanjing fire comes a month after 13 schoolchildren, aged nine and 10, were killed after a fire broke out in a school dormitory in China's Henan province.

Days later, at least 39 people were killed and nine injured in a fire that started in the basement of a shop in the city of Xinyu.