Twelve people suspected of being involved in the massive explosions at a chemical storage warehouse in Tianjin, China, have been arrested.
According to local media, they included the chairman, vice-chairman and three deputy general managers of the logistics company which had been storing the volatile chemicals.
The blasts killed 139 people and injured hundreds more, leaving the port area of the city in ruins.
Chinese officials have acknowledged the presence of toxins at the site of two massive explosions in a warehouse district in the city of Tianjin, but said they pose no risk to people outside the two-km evacuation zone.
"I can responsibly say that there will be no secondary damage to the people," Shi Luze, the chief of staff of the People's Liberation Army's Beijing Military Region, told reporters, referring to people outside the zone.
Mr Shi confirmed the presence of more than 100 tons of deadly sodium cyanide, stored at two separate sites.
He said workers were trying to clear the area of chemicals before possible rain showers, which could create toxic gas.
Thousands of dead fish have washed up near the site of two explosions which killed at least 114 people in China.
China's authorities face increasing pressure for answers and assistance from citizens left homeless after the devastating factory explosion.