Huge explosions in a warehouse district killed at least 44 people and injuring hundreds in the Chinese port city of Tianjin, officials and witnesses said on Thursday.
At least 520 people were injured, more than 60 of them seriously, the Tianjin government said on its Weibo microblog, and the People's Daily newspaper said four fires were still burning.
Wednesday night's blasts, so large that they were seen by satellites in space, sent shockwaves through apartment blocks kilometres away in the port city of 15 million people.
The blasts , originating at a warehouse for hazardous material, knocked doors off buildings in the area and shattered windows up to several kilometers away.
"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. "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."
Zhang said she could see wounded people weeping. She said she did not see anyone who had been killed, but "I could feel death."
There was no indication of what caused the blasts, and no immediate sign of any large release of toxic chemicals into the air. The Beijing News newspaper reported on its website that there was some unidentified yellow foam flowing at the site.
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 is properly approved to handle such materials. State media said senior management of the company had been detained by authorities, and that President Xi Jinping has demanded severe punishment for anyone found responsible for the explosions.
The official Xinhua News agency said an initial explosion triggered other blasts at nearby businesses. 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 explosions took place in a mostly industrial zone, with some apartment buildings in the vicinity. Buildings of a half-dozen other logistics companies were destroyed in the blasts, and more than 1,000 new Renault cars were left charred in a nearby parking lot, the Beijing News said.
'Fireball high in the sky'
Photos taken by bystanders and circulating on microblogs show a gigantic fireball high in the sky, with a mushroom-cloud. Other photos on state media outlets showed a sea of fire that painted the night sky bright orange, with tall plumes of smoke.
About 2 kilometers (1.2 miles) from the explosion site is the luxury Fifth Avenue apartment complex on a road strewn with broken glass and pieces of charred metal thrown from explosion. Like surrounding buildings, the Mediterranean style complex had all its windows blown out, and some of its surfaces were scorched.
"It's lucky no one had moved in," said a worker on the site, Liu Junwei, 29. "But for us it's a total loss. Two years of hard work down the drain."
"It had been all quiet, then the sky just lit up brighter than day and it looked like a fireworks show," said another worker on the site who gave just his surname, Li.
In one neighborhood about 10 to 20 kilometers from the blast site, some residents were sleeping on the street wearing gas masks, although there was no perceptible problem with the air apart from massive clouds of smoke seen in the distance.
"It was like what we were told a nuclear bomb would be like," said truck driver Zhao Zhencheng, who spent the night in the cab of his truck. "I've never even thought I'd see such a thing. It was terrifying but also beautiful."
At the nearby Taida Hospital as dawn broke, military medical tents were set up. Photos circulating online showed patients in bandages and with cuts.
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.
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.
Tianjin, with a population of about 15 million, is about 120 kilometers east of Beijing on the Bohai Sea and is one of the country's major ports. It is one of China's more modern cities and is connected to the capital by a high speed rail line.