State prosecutors in China said on Sunday they had started an investigation to see whether owners of the warehouse where the explosions occurred were guilty of violating laws on the storage of hazardous chemicals.

The announcement comes as authorities confirmed that hundreds of tons of the toxic chemical sodium cyanide had been on the site of the blasts late Wednesday evening in a mostly industrial area of the northern port city of Tianjin, 120 kilometers (75 miles) east of Beijing.

Such a large amount would be a clear violation of rules cited by state media that a maximum of 10 tons of the chemical may be stored at any one time. Chinese laws on hazmat storage also stipulate that such substances should not be kept closer than 1 kilometer from residential areas and public structures.

Sodium cyanide can form a flammable gas upon contact with water, and members of the public have questioned whether this fact had been taken into account by firefighters responding to the accident. At least 21 firefighters were among those killed in the warehouse fire and ensuing explosions, making the disaster the deadliest for the Chinese fire brigade in more than six decades.

Eighty-five of the 1,000 firefighters sent to combat the blaze remained unaccounted for on Sunday, with 88 bodies of victims still unidentified.

In addition to the 112 people confirmed dead, more than 700 people were hospitalized with sometimes serious injuries. Many were hurt by glass shattered in the huge fireballs that rose over the city on Wednesday night.

Official reassurances

In the face of internet rumors to the contrary, authorities have sought to reassure the public that the air in Tianjin remains safe to breathe, despite slightly raised levels of some pollutants.

In a bid to further dispel public mistrust, the Chinese premier Li Keqiang arrived in the city on Sunday afternoon and came within a kilometer of the blast site without wearing any form of protective clothing.

Li also visited those injured and displaced by the disaster.

The government has also shut down a total of 50 websites and 360 social media accounts for "creating panic by publishing unverified information or letting users spread groundless rumors," according to the Cyberspace Administration of China.

The Tianjin accident was one of the deadliest to occur in China in recent years. In June 2013, a fire at a poultry plant in the northeastern province of Jilin killed 121 people. In August 2014, 97 died in an explosion at a metal plant in eastern Jiangsu province.

tj/sgb (AP, dpa, AFP)