Police and labor ministry officials raided the on-site office of a petrochemical factory in the southern city of Yeosu on Monday to see if the company violated safety regulations in the wake of a deadly explosion that killed four workers and injured four others.

The explosion took place at the Yeochun NCC Co. factory in Yeosu, about 320 kilometers south of Seoul, on Friday while workers were conducting a test on a heat exchanger. Four people -- one employee of the petrochemical company and three employees of a subcontractor -- died and four others were injured.

Officials from the Ministry of Employment and Labor and police began searching the factory's office at 8:50 a.m. to see if the company violated the newly enacted workplace disaster law aimed at better protecting workers from industrial accidents.

Under the new workplace disaster law that took effect on Jan. 27, owners and CEOs of companies with five or more employees can face a minimum one-year prison sentence or up to a fine of 1 billion won ($834,000) in the event of serious workplace disasters.

"We are taking the accident very seriously as four deaths and four injuries happened in the explosion," a labor ministry official said, noting it is the second time an accidental explosion was reported at the petrochemical company since 2018.

Following the accident, the factory manager was booked on charges of violating the Occupational Safety and Health Act and the chief official on-site on charges of manslaughter by professional negligence. (Yonhap)