UPDATED at 02:25 P.M. EST on 2015-08-13
A series of massive blasts in China's northern port city of Tianjin shattered windows and rocked buildings up to three kilometers (1.8 miles) from the explosion, killing at least 50 people and leaving hospitals struggling to deal with the influx of injured, residents said on Thursday.
China's earthquake monitoring center said the first blast, which came as firefighters battled a blaze at a warehouse in the city, was the equivalent of three tonnes of TNT, and was followed by a second that was nine times as powerful.
Photos of the explosion, which the local government said killed at least 50 people, showed buildings and parked cars engulfed by a huge wave of flame.
"We felt the blast. It was like an earthquake," a doctor who answered the phone at the Tianjin No. 5 Hospital told RFA in the early hours of Thursday morning after the blast ripped through the port area late on Wednesday.
The doctor said that "more than 400 people" had been taken there with injuries following the blasts and fires.
The blast was powerful enough to shatter glass up to three kilometers away, local residents said.
"After the blast ... there was a huge shock wave and a lot of places lost power," a hotel employee three kilometers from the blast said.
"Windows shattered in the shock wave, and people were injured, including some people who received light injuries in this hotel, and some with more serious injuries, who went to hospital," he added.
Extensive damage and injuries
And employee who answered the phone at the Yilan International Hotel, also around three kilometers from the blast site, said the shock wave from the blast had caused extensive damage and injuries.
"Some of the glass in our hotel were shattered in the blast, some glass objects and also some windows," she said.
"We are on Boulevard 3; the blast was on Boulevard 5."
The doctor said health authorities were drafting in extra medical staff to help his hospital cope with the most serious injuries.
"We are adding up the figures now, and we have around 400 people, most of whom need emergency treatment. That's only at our hospital," he said.
"We are focused on saving patients now ... some of whom are pretty seriously injured," he said. "They are starting to refer more seriously injured patients to us here [from other hospitals]."
"Higher up is telling us to put all of our resources into it, and the Tianjin municipal health bureau has sent doctors here from elsewhere," he added.
Sources on the ground told RFA that the TEDA Hospital, just three kilometres from the blast, was also full of people seeking treatment for injuries, many of them serious burns.
"We just got out of the hospital," a local resident surnamed Weng said. "Several of our friends were injured, because the [building] we were in collapsed, and we all rushed out."
"But we were scattered, and when we gathered together again, there was one we couldn't find," Weng said.
Blood transfusion centers
The local blood transfusion service said it had set up five blood donation centers to try to meet demand in the wake of the explosion, they said.
According to online reports compiled by RFA's Cantonese Service, more than 1,200 people were injured in the blast. However, the Tianjin government reported 701 people were injured, of which 71 were in serious condition.
According to China's tightly controlled media, four of the warehouse fires were still burning on Thursday morning, as firefighters struggled to approach the blaze.
A firefighter contacted by RFA said the overall picture was still unclear after a nuclear, biological and chemical rescue team was deployed to the area.
"I don't know any details," the firefighter said. "I didn't go to the scene." He said three colleagues were still unaccounted for, however.
Local residents told RFA that police had sealed off the area surrounding the blast very quickly, and were warning local residents of the likelihood of further explosions, and advising them to leave as soon as possible.
But evacuating residents said there were no government assistance stations for them to move to, and that they had to find their own accommodation, and that all the hotels were full.
Both hotel employees contacted by RFA confirmed that their hotels were full, except for the most expensive suites.
Tight media curbs
But the ruling Chinese Communist Party has kept a tight leash on information about the disaster, establishing a security cordon around one mile from the site, keeping journalists and members of the public far from the scene.
"Tianjin" and "Tianjin" explosion were among the top restricted searches on the Twitter-like service Sina Weibo on Thursday, the anti-censorship site Free Weibo reported.
Deleted posts included those quoting CNN on the rising number of injuries and distressed local residents, a photo showing clouds of grey smoke engulfing a crowd on a city street, and information about movements to control social media posts linked to the incident.
"A lot of my classmates and friends are receiving notification from the propaganda department that no journalist, editor or TV presenter is to send tweets or messages to circles of friends, nor to retweet anything," user @liucuo wroted in a deleted post seen on Free Weibo.
Meanwhile, President Xi Jinping has called for "severe punishment" for anyone found responsible for the explosions.
China has a disastrous industrial safety record, and major chemical blasts in densely populated areas are not uncommon.
On July 20, a huge blast rocked the busy port of Rizhao in the eastern province of Shandong, followed by a large fireball local residents said was caused by an exploding liquid hydrogen explosion.
And in April, a large explosion ripped through a petrochemicals complex in the southeastern province of Fujian, following a string of earlier safety failures.
Six people were hospitalized following the blast, which rocked the Tenglong Aromatic Hydrocarbon (Zhangzhou) Co on the Gulei peninsula outside Fujian's Zhangzhou city, official media reported at the time.
Reported by Ka Pa and Lam Lok-tung for RFA's Cantonese Service, and by Xin Lin for the Mandarin Service. Translated and written in English by Luisetta Mudie.