Klang Utara police chief S Vijaya Rao said those injured, aged between 20 and 40, were in the vicinity when the explosions occurred.

“All of them are locals. They received outpatient treatment at Tunku Ampuan Rahimah Hospital and were allowed to return home. No serious injuries were reported,” Bernama reported him as saying.

Police, firefighters and officers from the Klang health office continued conducting inspections at the site today.

Earlier, Selangor environment department director Nor Aziah Jaafar reportedly said possible negligence and violation of licence conditions were among the factors being investigated in connection with the incident.

Selangor police chief Hussein Omar Khan said initial investigations indicated that the explosions were caused by chemicals stored in the plant’s compound.

The Selangor fire and rescue department said a hazardous and toxic materials team found that the chemicals were recycled acid.