天津塘沽爆炸防止二次灾难

Chemical specialists investigating the blasts believe sodium cyanide, a highly toxic inorganic compound might have been stored at the site.

Gao Huaiyou, deputy director of Tianjin's work safety watchdog, says containers at the blast site are closed and some haven't been registered, so the exact amount of the dangerous chemical is not yet clear.

"First, the authorities in Tianjin have dispatched local personnel from chemical enterprises that produce sodium cyanide to come to the blast site to deal with the highly-toxic materials. Secondly, the work safety administration has sent a team of professional personnel to spray hydrogen peroxide to neutralize sodium cyanide, in order to reduce the poison to a minimum."

The official notes that some other dangerous chemicals likely to be stored include potassium nitrate and ammonium nitrate.

The military's Anti-chemical corps has been sent into the center of the blast zone to verify what's in the storage containers.

At the same time, the rescue operation continues within the area.

A man in his fifties was found alive on Saturday and sent to hospital for treatment.

Doctors say he has serious injuries including ruptures to his right lung and kidney.

This comes after a 19-year-old firefighter was pulled out alive on Friday.

Minor explosions and fire were reported at the warehouse Saturday.

This has forced rescuers to vacate the site temporarily.

Residents in a relocation site at a primary school were also evacuated after concerns of chemical pollutants in the air due to a change of wind direction.

A total of 70 firefighters and eight fire trucks are monitoring the blast site.

Zhou Tian, head of Tianjin Fire Department.

"So far there is no open flame at the explosion site. But as various dangerous chemical items are mingled there, they still give out heat and there are also smoke rising from places where containers piled up."

Another 1,100 troops have been deployed to comb nearby residential quarters to search for potential survivors.

Many of the burn victims from the explosions remain in critical conditions.

Doctors say they face increasing difficulties treating the blast victims as most of them suffer from multiple injuries.

"These victims have complicated injuries, not simply caused by scalding or burns. They also suffer blast injuries and chemical poisoning."

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

For CRI, I'm Wang Mengzhen.