Firefighting efforts at China's warehouse explosion site have been suspended due to lack of clarity about the contents and amount of the "dangerous goods" in the warehouse, according to a local government statement on Thursday.

The Binhai New District government in Tianjin city made the announcement on its official weibo.

Two massive explosions caused by flammable goods ripped through an industrial area in the northeast Chinese port of Tianjin late on Wednesday, killing 17 people and injuring as many as 400.

Nine firefighters have been confirmed dead, state television said on Thursday.

CCTV said the blasts erupted in a shipment of explosives at around 11:30 p.m. local time (1530 GMT), triggering a blast wave that was felt kilometres (miles) away. The second blast came roughly 30 seconds after the first, state media said.

Xinhua said the explosions had ripped through a warehouse storing "dangerous goods". The first explosion was equivalent to 3 tonnes of TNT and the second blast 21 tonnes of TNT, it said.

Residents in nearby areas said the blasts had shattered windows in buildings, it reported.

Citing a local hospital, Xinhua said people had been hurt by broken glass and stones and some were seriously wounded.

People react near a street after a blast at Binhai new district, in Tianjin municipality, China, August 12, 2015. Photo: Reuters

Smoke rises over Tianjin Port after explosions hit the Binhai new district in Tianjin August 13, 2015. Photo: Reuters

A man wearing a mask walks past overturned shipping containers after explosions hit the Binhai new district in Tianjin August 13, 2015. Photo: Reuters

An injured man (R) looks on near the site of the explosions at the Binhai new district in Tianjin, China, August 13, 2015.  Photo: Reuters

Damaged vehicles are seen under bridges close to the site of the explosions at Binhai new district, Tianjin, August 13, 2015. Photo: Reuters

A man who was injured following the massive explosions at the Binhai new district in Tianjin receives medical treatment at a hospital, Photo: Reuters

A man wears a mask while resting outside after explosions hit Binhai new district, Tianjin, August 13, 2015. Photo: Reuters

Damaged cars are seen as smoke rises from the debris after the explosions at the Binhai new district in Tianjin, China, August 13, 2015. Photo: Reuters

People wearing masks look on near the site of the explosions at the Binhai new district in Tianjin, China, August 13, 2015. Photo: Reuters

Smoke rises from shipping containers after explosions at Binhai new district in Tianjin, China, August 13, 2015. Photo: Reuters

Damaged vehicles are seen as smoke rises from shipping containers after explosions at Binhai new district in Tianjin, China, August 13, 2015. Photo: Reuters

Workers clean debris on a highway near the site of the explosions at the Binhai new district, Tianjin, August 13, 2015. Photo: Reuters

Damaged vehicles are seen near the site of the explosions at the Binhai new district, Tianjin, August 13, 2015. Photo: Reuters

Overturned containers are seen near the site of the explosions at the Binhai new district, Tianjin, August 13, 2015. Photo: Reuters