Chinese prosecutors have detained 11 government officials and company executives over a massive warehouse explosion that killed at least 139 people in the country's worst industrial disaster in recent years.

A notice on the national prosecutor's website said Thursday they included current and retired officials in the port city of Tianjin, along with others working for the company that runs the port, the largest in northern China.

All are accused of dereliction of duty and abusing their positions, the notice said.

The Aug. 12 explosions at the warehouse owned by Ruihai Logistics were not only one of China's worst accidents but the deadliest ever for first responders, with 115 police and firefighters among the dead and missing.

The investigation has focused on how the warehouse gained permission to handle sodium cyanide and other dangerous chemicals despite being located inside a legally-mandated 1,000-yard buffer zone from homes and roads. The investigation has also found that the warehouse was storing more chemicals than it was equipped to handle and had kept some in a loading zone rather than storing them securely.

The responsible parties "failed to take strong measures in response to the Ruihai company's illegal and unregulated actions, did not assiduously carry out their duties and issued business permits in violations of rules," the prosecutor's notice said.

Police have already detained 12 Ruihai employees as part of their investigation and are also looking into a company suspected of providing bogus safety assessments.