The death toll from massive explosions at an industrial area in the Chinese port of Tianjin is reported to have risen to 50.
Twelve firefighters were among the dead, the official Xinhua news agency said, citing rescue officials.
More than 700 people were injured, more than 71 of them seriously.
The blasts ripped through an industrial area where toxic chemicals and gas were stored in the northeast port city of Tianjin last night.
They were so large that they were seen by satellites in space.
The explosions sent shockwaves through apartment blocks kilometres away in the port city of 15 million people.
Internet videos showed fireballs shooting into the sky and the US Geological Survey registered the blasts as seismic events.
Vast areas of the port - the tenth largest in the world - were devastated.
The first blast was said to have been equivalent to three tonnes of TNT and the second the same as 21 tonnes of TNT.
Shipping containers were thrown around like match sticks, hundreds of new cars were torched and port buildings were left as burnt-out shells, Reuters witnesses said.
President Xi Jinping demanded that authorities "make full effort to rescue and treat the injured and ensure the safety of people and their property".
Mr Xi said in a statement that those responsible should be "severely handled".
Fires were still burning after dawn.
A witness said several trucks carrying paramilitary police - wearing masks to protect them from potentially toxic smoke - headed to the area.
The blasts shattered windows in buildings and cars, and knocked down walls in a 2km radius around the site.
Guan Xiang, who lives 7km from the explosion site told Reuters: "I was sleeping when our windows and doors suddenly shook as we heard explosions outside. I first thought it was an earthquake."
He said he saw flames and a mushroom cloud in the sky as he and other residents scrambled to get out of the building.
Burned-out cars were seen inside a multi-storey car park at a logistics base at Tianjin Port.
A video posted on YouTube from what appeared to be an apartment building some distance from the scene showed an initial blast followed by a second, much bigger, explosion.
Shockwaves hit the building seconds later.
Media said workers had temporarily ceased efforts to put out remaining fires by mid-morning because it was unclear what types of chemicals were stored in the area.
Other outlets said a chemical specialist team had been sent to the site.
About 100 fire trucks were reportedly sent to the scene, but several of them had been destroyed.
