Chinese authorities have ordered the evacuation of a 3-kilometre zone around the northern port city of Tianjin over chemical contamination fears from blasts and fires that continue to rage.
Police and military staff are deployed at checkpoints leading to the explosion site, and helicopters are hovering above.
The death toll from blasts that began at a warehouse storing hazardous materials has reached 104, including 21 firefighters. Burning flames were still visible on Saturday, and explosions have been reported by witnesses and state media.
Authorities are yet to determine the full list of chemicals on site. State media say there are large amounts of sodium cyanides, which is combustible upon contact with water.
The People’s Daily newspaper tweeted that the authorities had been sent to handle highly toxic sodium cyanide, which had been found there. The discovery was confirmed by police “roughly east of the blast site” in an industrial zone, State-run Beijing News said.
Officials had until then only confirmed the presence of calcium carbide, potassium nitrate and sodium nitrate. Calcium carbide reacts with water to create the highly explosive acetylene. Officials have so far insisted that air and water quality levels are safe. The chemical sodium cyanide is white crystalline or granular powder, which can be rapidly fatal if inhaled or ingested, as it interferes with the body’s ability to use oxygen.
It is mostly used in chemical manufacturing, for fumigation and in the mining industry to extract gold and silver.