Grey clouds of smoke billow above the blast site in Tianjin two days after massive explosions in the northern Chinese port city, as firefighters continue their efforts to halt residual fires according to drone and aerial footage from the blast site shared on social media on Friday.
The explosions occurred about 11:30 pm local time (15:30 GMT) on Wednesday at a warehouse site owned by Tianjin Dongjiang Port Rui Hai International Logistics Co. which stores and transports dangerous chemicals, the Tianjin government said on its Weibo microblog.
Following the blast, more than 55 people lost their lives and 701 were hospitalised, including 70 who are in critical condition.
China Central Television reported that 16 firefighters have been killed so far and 13 are still missing.
According to China's official Xinhua news agency 66 firefighters are among the hundreds of people undergoing treatment in hospitals in the area.
The devastating blast was so large, it was seen by satellites in space. Residents in nearby districts said the blast shattered the windows of many homes.
The instability of the situation has caused panic in the city due to fears over a variety of dangerous chemicals continuing to blow up, threatening the lives of more than 90,000 people who live within a 5 kilometer radius of the blast site, according to the Chinese Earthquake Administration.
On Thursday 217 nuclear and chemical experts from the Chinese military rushed to the site to collect evidence to determine the cause of the two massive explosions in the warehouse filled with hazardous chemicals, Xinhua reported.
The National Health and Family Planning Commission also sent 36 clinical and psychological specialists from 10 civil and military hospitals located in China's capital city, Beijing.
Nearly 1000 firefighters also attempted to calm the ongoing fires and blasts as local residents expressed their concern about the dangerous situation.
The country’s ministry of environmental protection said on Friday that cyanide and other dangerous toxic chemicals - mainly ammonium nitrate, potassium nitrate and calcium carbide - were being stored in the warehouse at the time of the blasts.
According to an initial statement by the experts who continue to work on the damaged site, water sprayed on chemicals by firefighters triggered the bloody explosion.
Chinese police also gave information about the explosions, saying that calcium carbide was among the dangerous chemicals stored in the warehouse which reacted with water when it was used by the firefighters to control the blazes and created the highly explosive gas acetylene.
Although the first group of firefighters who arrived on the scene were accused of causing the blast by using water, Chinese officials defended them, saying that it was impossible to determine the exact location of the calcium carbide.
Lei Jinde, the deputy propaganda department head of China's fire department - a part of the Ministry of Public Security - told state-backed news website ThePaper.cn, "We knew there was calcium carbide inside but we didn't know whether it had already exploded."
"At that point no one knew, it wasn't that the fire fighters were stupid," he added.
According to David Leggett, a chemical safety expert based in California, the acetylene explosion could have detonated the ammonium nitrate at the plant. There was only about 30 minutes between the two blasts and the second was much more powerful than the first.
"In my mind, the presence of ammonium nitrate makes it easier to explain the level of devastation," he said.
Stuart Prescott, a senior lecturer in chemical engineering at the University of New South Wales in Australia, said water was recommended to control the fire involving the two nitrates but a chemical powder was needed for calcium carbide.
"Calcium carbide reacts with the water and that's a reasonably violent reaction in and of itself, because it releases gas. The gas itself is also flammable," he said.
The People's Daily, a paper backed by the ruling Chine Communist Party, said that the facility’s construction "clearly violated" safety rules.
According to Chinese regulations, warehouses with dangerous materials must be located at least 1km away from city centers, public buildings and main roads.
A week ago, city officials and company managers gathered to discuss tightening safety standards over the storing of hazardous chemicals. After the meeting the Tianjin Administration of Work and Safety posted the results of the discussion on its website.