RESCUE efforts continued yesterday at a chemical plant in eastern China where six people remained missing after a massive explosion.

Tuesday’s blast in Weifang, a city in Shandong province, killed at least five people and injured 19.

It was not immediately clear what had caused the explosion, which occurred at a plant owned by the Gaomi Youdao Chemical Company, a producer of pesticides and chemicals for medical use with more than 500 employees.

A student at a school around half a mile away from the plant told news website The Paper that he had heard an explosion and saw dirt-yellow smoke, tainted with redness, rising from the plant. 

The blast came less than two weeks after the National Ministry of Emergency Management held a workshop on preventing and controlling risks in the chemical industry, as Beijing urged officials at chemical industrial parks to boost their capabilities in “managing hazardous chemicals.”

Last year, the chemical plant was cited for “safety risks” at least twice.

Workplace safety in China has improved over the years, but, in common with many countries, remains a stubborn problem.

The National Ministry of Emergency Management recorded 21,800 incidents and 19,600 deaths last year.