The fire brigade stand ready to evacuate local residents from a blast site in Tianjin, Aug 13, 2015. [Photo/IC]

EVACUATION

Several small blasts rocked the site again Saturday morning, triggering fire and dense smoke and forcing rescuers and others to vacate the site temporarily.

Residents in a relocation site at a primary school also were evacuated in fear of chemical pollutants in the air after receiving an alert of wind change.

Specialists investigating in the massive explosions in Tianjin believed the existence of sodium cyanide, a highly toxic inorganic compound, is "possible".

Gao Huaiyou, vice head of the Tianjin administrative bureau of work safety, said in a press conference Saturday afternoon that the dangerous chemicals stored in the warehouse possibly include sodium cyanide.

But he said further confirmation is still needed, because the containers were not open, and some even not registered. He was not sure how much sodium cyanide, if any, was in storage at the time of blasts.

Some local media reported earlier that Rui Hai International Logistics, owner of the warehouse which is licensed to store dangerous chemicals, had as much as 700 tonnes of sodium cyanide, but Gao said it was not yet verifiable.

Measures have been taken to prevent secondary disasters, such as inviting sodium cyanide producing enterprises to help at the site, using hydrogen peroxide to reduce the amount of sodium cyanide, sending a special taskforce to locate and measure the area contaminated by sodium cyanide, and prevent its spreading in sewage.

Some other dangerous chemicals likely to be stored included potassium nitrate, ammonium nitrate.

The warehouse was owned by Tianjin Dongjiang Port Rui Hai International Logistics Co. Ltd., which was founded in 2011 and is a storage and distribution center of containers of dangerous goods at the Tianjin Port.

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