The impact of the blast could be felt miles away, Reuters reported, citing local media. The National Earthquake Bureau reported two major blasts before midnight, the first with an equivalent of 3 tons of TNT, and the second with the equivalent of 21 tons.

The explosives were stored in a warehouse in the city's Binhai New Area, according to China's Xinhua News Agency. The fireballs generated from the initial blast caused addition explosions in nearby businesses, the news agency reports.

CCTV reported that the initial explosion involved a shipment of explosives at a container port which blew up around 11:30 p.m. local time.

The explosion happened in a section of an industrial park, with some apartment buildings in the vicinity.

"I thought it was an earthquake, so I rushed downstairs without my shoes on," Tianjin resident Zhang Siyu, whose home is several kilometers from the blast site, said in a telephone interview with the Associated Press. "Only once I was outside did I realize it was an explosion. There was the huge fireball in the sky with thick clouds. Everybody could see it.".

A massive explosion rocked the northeastern Chinese city of Tianjin Wednesday, leaving at least 17 people dead and hundreds injured, according to media reports.

"I thought it was an earthquake, so I rushed downstairs without my shoes on," Tianjin resident Zhang Siyu, whose home is several kilometers from the blast site, said in a telephone interview with the Associated Press. "Only once I was outside did I realize it was an explosion. There was the huge fireball in the sky with thick clouds. Everybody could see it.".

Tianjin is located about 70 miles southeast of China's capital, Beijing.

Ruihai Logistics says on its website that it was established in 2011 and is an approved company for handling hazardous materials. It says it handles 1 million tons of cargo annually.

Buildings near the blast site had visible cracks in them, China National Radio reported.

China's state broadcaster, CCTV, said that at least 17 people were killed and that 32 were in critical condition in hospital. The state-run Beijing News said on its website that between 300 and 400 people had been admitted to hospitals in the city.

Photos apparently taken by bystanders and circulating on microblogs show a gigantic fireball high in the sky, with a mushroom-cloud, the South China Morning Post reported. Other photos on state media outlets showed a sea of fire that painted the night sky bright orange, with tall plumes of smoke.

Zhang said she could see wounded people weeping. She said she did not see anyone who had been killed, but "I could feel death.".

State broadcaster CCTV said six battalions of firefighters had brought the ensuing fire under control, although it was still burning in the early hours of Thursday.

Police in Tianjin said an initial blast took place at shipping containers in a warehouse for hazardous materials owned by Ruihai Logistics, a company that says it's properly approved to handle hazardous materials. State media said senior management of the company had been detained by authorities.