Authorities in China last week released the details of their investigation into an August 2015 chemical blast that killed 165 and injured hundreds more in the port city of Tianjin.
The Associated Press, citing the official Xinhua News Agency, reported that the probe attributed the explosion to flammable nitrocellulose stored at Ruihai International Logistics Company's unlicensed warehouses.
The highly flammable nitrocellulose — which is used in medical applications and lacquers — lost humidifying agents and dried out in the height of summer, then ignited when overheated.
Flames then spread to illegally stored ammonium nitrate fertilizer at the Ruihai complex, which fueled two immense explosions.
An investigator also told state TV that firefighters responding to the fire were not aware of the ammonium nitrate stored on site. Ninety-nine firefighters died in the blasts.
In addition, state media indicated that 25 more people would face charges related to the blast, including suspicion of dereliction of duty, abuse of power and bribery. Dozens were previously arrested for failing to enforce safety regulations.
Authorities alleged that Ruihai mischaracterized its plans for the warehouses and colluded with local officials to secure government approval.
"If the proper approval procedures had been followed, Ruihai would have never been allowed to exist in the first place," investigator Li Wanchun told state TV.