Tianjin, a city of 7.5 million people, is near the East China Sea on the northeastern coast of China, roughly 90 miles southeast of Beijing.
Residents in nearby areas said the blasts had shattered windows in buildings, it reported.
Police in Tianjin said an initial blast took place late Wednesday night in shipping containers at a warehouse for hazardous materials owned by a logistics company. Unconfirmed reports said more than 300 people were wounded in the incident.
CCTV said the blasts erupted in a shipment of explosives at around 11:30 p.m. local time (1530 GMT), triggering a shockwave that was felt kilometres (miles) away.
Evacuees from the blast site have been brought into the Second Primary School in the Tianjin development area to be given emergency first aid and to assess their condition.
A video uploaded by Weibo Chinese social netowork showed alarming images of injured people walking around apparently disoriented, after the explosion.
Several fire trucks had been destroyed and nearby firefighters wept as they worked to extinguish flames, the Beijing News said.
Canadian teacher Monica Andrews told the BBC that she awoke in panic after what she thought was an quake.
China has a dismal industrial safety record as some factory and warehouse owners evade regulations to save money and pay off corrupt officials to look the other way.
In July, 15 people were killed and more than a dozen injured when an illegal fireworks warehouse exploded in the northern Hebei province. It is one of China’s more modern cities and is connected to the capital by a high speed rail line.