The mainland's top work safety official, who was overseeing the emergency response to the Tianjin blasts, was put under investigation for alleged corruption on Tuesday. But it was not clear if his detention was linked to the explosions that killed at least 114 people in the port city. The website of the graft-busting agency, the Central Commission for Discipline Inspection, said Yang Dongliang, head of the State Administration of Work Safety, was suspected of "violations of party discipline and the law", a euphemism for graft. The news came as a shock to many as Yang, a former deputy mayor of the city, had been overseeing the rescue efforts since the blasts last Wednesday. On Monday he attended a meeting of the State Council's rescue task force. Meanwhile, mainland media revealed 10 controllers and executives of Ruihai International Logistics, the operator of the warehouse where the blasts occurred, had been in police detention since last Thursday. Read more: Tears as Tianjin mourns victims of warehouse blasts in commemoration ceremonies across city Among those detained were Yu Xuewei, a former senior executive of Sinochem Tianjin, and Dong Shexuan, son of the former head of Tianjin Port Public Security Bureau, Caijing reported. Ruihai's temporary permit to handle hazardous chemicals had expired in October 2014, and it did not obtain another permit until June this year, mainland media reported. The probe into Yang, who built his career in petrochemicals and spent 12 years as a deputy mayor in Tianjin, might not be linked to the blasts. Mainland media said the investigation might instead be related to the loss of state assets in the city. Yang had been the head of the city's state-owned assets administration for five years. Inspection teams from the CCDI have not yet covered the work safety administration. The developments came as residents, firefighters, police and some officials gathered at sites in the Binhai New Area to remember those killed - carrying out a traditional ritual in marking the seventh day following a death. The authorities are yet to announce the cause of the blast and hazardous chemicals still need to be removed from the site. Some journalists and residents said they received skin burns after rain began to fall heavily at 10am. Experts have warned residents to stay away, fearing the rain could cause dangerous chemical reactions. Bao Jingling, chief engineer of the Tianjin Environmental Protection Bureau, said air quality would be closely monitored, but added, "the best way [to be safe] is to stay far away from the site". Angry homeowners braved the rain to protest outside a venue used for media briefings. They demanded compensation and asked the government to buy back flats damaged in the blasts. The State Council yesterday set up a task force to investigate the incident. It will be led by Vice-Minister of Public Security Yang Huanning. Wang Hongwei, a professor at Renmin University, expected more people would be investigated. He said the incident was "unprecedented" and that any official implicated, no matter how senior, would be punished.