Explosions at a warehouse containing hazardous materials rocked the Chinese port city of Tianjin on Wednesday, killing at least 50 and injuring over 700, 71 critically. Tianjin, 100 miles east of Beijing, is the fourth largest urban area in China. Buildings within a 1.5 miles radius had windows blown out, office blocks were destroyed and hundreds of cars caught fire.  Chemical and oil tankers have either been stopped from entering the port or discharging their cargoes for fear of further explosions.

The first explosion and fire at the Ruihai International Logistics warehouse, shortly after 11AM local time on Wednesday, was estimated to be the equivalent of 3 tons of TNT. The first blast is believed to have set off a second, much larger, explosion, equivalent to 21 tons of TNT.  The explosions registered between a magnitude 2 and 3 on the Richter scale in Beijing. The blasts caused a huge fireball that could be seen from space. Fires at and near the warehouse have been burning out of control. There is considerable concern about the toxicity of the chemicals burning in the fires.

As reported by the New York Times:

According to the Tianjin Tanggu Environmental Monitoring Station, the company stored a collection of toxic industrial chemicals, including sodium cyanide, toluene diisocyanate and calcium carbide. The company was also licensed to handle highly combustible substances such as compressed and liquefied natural gas.

In a statement on Thursday, Greenpeace warned that many of the substances posed worrying threats to human health. It said that sodium cyanide, a compound used in mining, is especially toxic, while toluene diisocyanate, used in the making of polyurethane products, is a known carcinogen and highly explosive.

With rain forecast for Friday, Greenpeace warned about the danger of airborne pollutants seeping into local groundwater supplies. The disclosure that dangerous chemicals were stored less than a mile from dense residential areas raised questions about the government’s role in monitoring operations at the site.

Thanks to Phil Leon for contributing to this post.