Executives of a chemical plant in China’s Jiangsu province have been taken into police custody after an explosion on Thursday killed at least 64 people, injured 640 others and polluted areas several kilometres away. Cao Lubao, mayor of Yancheng, where the blast occurred, said on Friday that nearly 3,000 people – employees of nearby plants and residents – had been evacuated after the explosion at the Jiangsu Tianjiayi Chemical plant in the township of Chenjiagang, which left a giant crater. Schools and kindergartens had been closed while the authorities monitored air and water quality, Cao said. President Xi Jinping, who is visiting Italy, said no effort should be spared to rescue trapped people and treat the injured. He also demanded that all levels of government strengthen inspection procedures. Thirty-four people were in a critical condition and 60 were seriously injured, while 28 were still missing as of late Friday. The Ministry of Emergency Management said 88 people were rescued from the scene. Visible flames had been put out but the whole of Xiangshui Ecological Chemical Industrial Park, where the plant is situated, was still engulfed by heavy smoke on Friday morning. Jiangsu Tianjiayi Chemical plant was flattened and 16 neighbouring factories were left with varying degrees of damage. The impact smashed windows and uprooted roofs of some buildings and reduced others to rubble. Chemical plant explosion boosts China dye stocks, sinks affected firms Early on Friday, injured people streaming into the emergency ward at Xiangshui People’s Hospital – one of the biggest in Xiangshui county, about 300km north of Shanghai. State news agency Xinhua released a video of a man calling out to his family just after he was pulled from the rubble on Thursday night. “I am out. Firefighters rescued me. I am fine, just some minor injuries,” the man said, gasping. The plant had been flattened and reduced to rubble, with only part of the workshop frame still standing. China chemical blast: relatives grieve and villagers flee like refugees A survivor who was standing by the roadside 1½km from the factory said the impact blew him and two of his friends off their feet, sending them tumbling in the air. “The air blast hit us and sent us up in the air,” the man, surnamed Lan, told the Beijing News . “I can’t describe it. It was horrifying.” They drove themselves to hospital in a car badly damaged in the blast. “I couldn’t get through on 120 [ambulance hotline] at all,” Lan said. “We had no other means but to drive this broken car … One had an injured foot and the other had damage to his internal organs.” Workers at the Henglida Chemical Factory, 3km from the blast, said its windows and doors were blown out. Its roof collapsed as they tried to escape, causing head injuries. Residents from Yancheng and nearby cities queued past midnight to donate blood. The deadly blast caused pollution in the area’s air and rivers. Tests on Friday morning 3½km downwind from the explosion site found levels of nitrogen oxides that were almost twice the national air safety level for industrial zones, capable of causing respiratory infection, the Jiangsu Ecology and Environment Department said. Explosions and landslides – China’s worst accidents since 2014 All three of the rivers in the industrial park were polluted with levels of dichloroethane and dichloromethane that exceeded the national surface water quality standard by 2.8 times and 8.4 times respectively, it said. Water checks did not find any volatile organic compounds outside the gate of the industrial park or 3km downstream of the sewage discharge point. Local authorities were taking measures to prevent polluted water flowing outside the park.