The explosion happened just before noon yesterday at a facility operated by Shandong Youdao Chemical in the city of Gaomi, sending plumes of orange and black smoke into the sky.

Nineteen people were injured and six more remain missing, according to the state-run Xinhua news agency.

Local officials have not yet released the results of unspecified tests carried out at the site.

The streets leading up to the smouldering ruins were deserted, except for emergency teams, Reuters’ witnesses reported.

Black and grey smoke was still rising from the facility, although there was no sign of a fire that national-level authorities yesterday had urged emergency workers to quickly contain.

Shandong Youdao Chemical was established in August 2019 in the Gaomi Renhe chemical park, according to the company’s website.

The plant develops and produces chemical components for use in pesticides and pharmaceuticals, employing more than 300 people on a site of more than 47 hectares.

The company is a unit of Himile Group, which also owns listed Himile Mechanical, whose shares were down nearly 3.6% when the market closed yesterday.