The final cleanup gets underway at the warehouse blast site in Tianjin on Friday. All of the containers, damaged vehicles and buildings at the site have been removed. Jia Chenglong / for China Daily

More than 120 people have been held responsible for the massive explosions in Tianjin in August that killed 165 and devastated the port area, according to an investigation report released on Friday.

Forty-nine people have been detained. Public security authorities are conducting criminal investigations into 24 staff members from related enterprises, including 13 from Tianjin International Ruihai Logistics Co, which owns the warehouse where the explosions occurred.

In addition, 25 officials from the port, customs, work safety and transportation sectors are being investigated.

Apart from them, disciplinary punishments are suggested for 74 people, including five at the ministerial level, said the report by the State Council's investigation team.

The explosions occurred in Tianjin Binhai New Area on Aug 12. In addition to the deaths, 798 people were injured and eight missing, and economic losses of more than 6.8 billion yuan ($1.03 billion) were reported.

The investigation found that the disaster was caused by ignition of hazardous materials improperly or illegally stored at the site.

The fire started in a container through auto-ignition of nitro-cotton, due to vaporization of the wetting agent during hot weather. The fire spread, igniting other chemicals, including 800 tons of ammonium nitrate.

Du Lanping, head of the investigation team's technical group, said that storage of such a large amount of chemicals was illegal because of the high risks involved.