Tianjin blasts
A firefighter stands on top of a fire truck as smoke rises amid shipping containers at the site of Wednesday night's explosions, at Binhai new district in Tianjin, China, Aug. 14, 2015. Reuters/Stringer

Chinese Premier Li Keqiang has ordered a nationwide "overhaul of work safety" that focuses on dangerous chemicals and flammable materials, the state-run Xinhua news agency reported Sunday. Investigators are still trying to find evidence to explain the blast, but Li met with rescue workers Sunday and ordered the evidence gathered so far be released to the public.

Reports emerged Sunday Chinese officials have found hundreds of tons of sodium cyanide at two locations within the site of last week's blasts, the Guardian reported. The discovery came after state media this weekend claimed as much as 700 tons of sodium cyanide, 70 times the permitted amount, were stored at the site and may have caused the blast.

"The accident has incurred heavy casualties and taught us an extremely painful lesson," Li said at the meeting, according to Xinhua.

At least 112 people were killed in the blasts and about 700 were injured, the Associated Press reported Sunday. Some media outlets, though, said the death toll already may have risen to 200.

The investigation and rescue efforts are already causing companies in the area to halt production, especially in the automotive sector. Tianjin is the gateway to northeast, China and about 40 percent of China's imported cars enter the country there.

Toyota Motor Corp. will not resume its operations near the Chinese port of Tianjin until Thursday, officials of the company said Sunday, because rescue workers and officials still are clearing the blast site and looking for the 100 people still missing. The company said in a statement its production levels have not been affected by the explosion last week because it took place during its holiday.

But that could change in upcoming days, the company said Sunday. "Due to ongoing evacuation advisories, none of the three lines at Tianjin FAW Toyota Motor Co Ltd will be [in] operation from Aug. 17-19," Toyota said, Reuters reported. Another line at Xiqing, about 44 miles away, also shut down because it needs parts produced at the Tianjin facility.