A massive explosion hit a "dangerous goods" warehouse in Tianjin, China, on Wednesday, killing at least 50 people and leaving emergency services staff trapped in the rubble.
The explosion in the Binhai New Area on the city's coast happened at about 11.30pm local time, with videos posted on social media showed a towering inferno above one of China's largest urban areas.
Reuters cited a statement by the city's government that 50 people were confirmed dead - including 12 firefighters - and as many as 700 injured, over 71 seriously. The Beijing News, an official outlet, reported that authorities had lost contact with 36 firefighters on the scene.
As many as eight fire engines were destroyed by the blast. Nearby, firefighters wept as they worked to extinguish the flames, Beijing News reported.
Read More Scenes from the devastating Tianjin explosion
Chinese President Xi Jinping ordered a fast and comprehensive rescue operation, and promised a thorough investigation and severe punishment for any wrongdoing.
Shares of companies in the Binhai economic development zone dropped sharply, against gains on the main indexes, and Tianjin Port Development halted trading in its shares in Hong Kong without giving a reason. Trading a shipping sources told Reuters Thursday that chemical and oil tankers had either been stopped from entering the port or discharging their products for fear of further explosions.
CCTV and the People's Daily reported that crews of firefighters and rescue teams arrived at the warehouse at about 10.50pm to tackle a fire, and were then trapped by the subsequent blasts.
Citing the China Earthquake Networks Centre, Dow Jones reported that seismologists had tracked two explosions at about 11.34pm. The second blast was equal to about 21 tons of TNT exploding, while the first was the equivalent of about 3 tons of TNT, according to numerous reports.
CCTV said that the blast could be felt miles away from the scene in the port city.
Dow Jones reported that the warehouse is used by Ruihai International Logistics, a company that handles hazardous materials, citing a blog run by China's Ministry of Public Security Fire Department.Some local reports indicated that residents had been warned to close their windows in case of hazardous gases.
Canadian teacher Monica Andrews told the BBC that she awoke in panic after what she thought was an earthquake.
"I ... looked out the window and the sky was red ... I just watched a second explosion go off and (it was) just pure chaos, everyone leaving their apartment buildings thinking it's an earthquake, cars trying to leave the complex and ...it was crazy the amount of light that this explosion and fire lit up," she said.
Videos of the explosion showed flames lighting up the night sky and state-run news agency Xinhua quoted residents in nearby districts as saying the blast had shattered windows. In the videos, residents and workers could be seen fleeing the scene.
CCTV reported that about 100 fire trucks had been sent to the scene. Xinhua said fireballs from an initial blast had ignited further explosions in premises nearby.
Tianjin is one of the largest cities in China, two hours' drive away from Beijing, with an estimated population of more than 15 million people.
Industrial accidents are not uncommon in China following three decades of breakneck economic growth. A blast at an auto parts factory in eastern China killed 75 people a year ago when a room filled with metal dust exploded.
—Reuters and the Associated Press contributed to this report.