Tianjin explosions’ death toll has risen to 44 as more than 500 people were injured.

Twelve firefighters were among the dead, China’s official Xinhua news agency said as it reported a doubling of the death toll following two major explosions in the northern port city.

The blasts happened in a warehouse storing “dangerous and chemical goods” in the port area of Tianjin.

The explosions caused a huge fireball that could be seen from space.

Buildings within a 1.5 miles had windows blown out, office blocks were destroyed and hundreds of cars burnt-out.

Images on Chinese media showed local residents and workers fleeing their homes, some of them covered in blood from broken glass and flying debris.

As of 12:00 local time, 44 people had died and a total of 520 people had been hospitalized, including 66 in a critical condition, Xinhua reported.

The first explosion occurred at about 23:30 local time on August 12, followed seconds later by another, more powerful blast and a series of smaller explosions. The impact could be felt several miles away.

The China Earthquake Networks Centre said the magnitude of the first explosion was the equivalent of detonating three tonnes of TNT, while the second was the equivalent of 21 tonnes.

State broadcaster China Central Television (CCTV) said a shipment of explosives had detonated but this has not been confirmed.

Senior managers of Ruihai Logistics, which owns the warehouse where the explosion happened, are being questioned by authorities, state media report.

China National Radio also said cracks were visible in buildings near the site of the blast.

Several tower blocks near the port area are without power, CCTV added.

Tianjin, home to some 15 million people, is a major port and industrial area to the south-east of the Chinese capital, Beijing.