The blasts ripped through the Ruihai warehouse, which stores dangerous goods, at 11.20 PM local time yesterday, following a fire report half an hour earlier.
Fireballs erupted then ignited more explosions in companies nearby, according to rescuers, state-run Xinhua news agency reported.
It said 44 people, including 12 fire fighters, have been killed and 520 others injured in the explosions.
The massive blasts were caused by combustible and explosive goods stored in containers at the warehouse, official People’s Daily online reported.
Chemicals at a container terminal exploded in Binhai New Area in Tianjin.
State-run CCTV showed footage of massive explosions in the city. More than 10,000 people were reportedly evacuated from the nearby areas.
The condition of 66 injured was stated to be serious.
In the video, huge mushroom cloud and fire can be seen far off. Fire still raging at the place of explosions with huge smoke billowing out.
The TV report said the fire still yet to be contained as firefighters can not use water to put it out due to presence of chemicals and instead has to use sand and other materials to contain it.
Xinhua reported that there are people trapped inside the blast site and rescue operation is still going on. The injured have been sent to several hospitals nearby.
Blood can be seen everywhere on the floors of hospitals.
Lu Yun, head of Taida Hospital, which has admitted some 150 injured people, told Xinhua that the injuries were mostly from broken glass or stones.
The shockwaves were felt kilometres away, with window glass of buildings shattered.
The rolling doors and window glass of Donghai Road terminal station of Jinbin light railway, which serves as a major link between the Binhai New Area and the downtown Tianjin, were broken. Its roof also partially collapsed.
Minor fires and blasts could still be seen from a far distance early today.
As soon as the explosion was under control, some taxi drivers and private car owners have voluntarily helped with sending the wounded to hospitals.
Some hotels have provided free accommodation to residents displaced by the blast.