Police and the Ministry of Employment and Labor raided Aricell and partner companies that sourced workers for its battery plant on Wednesday to investigate irregularities in their operations after a deadly fire killed 23 workers and injured eight earlier in the week.

The move came a day after the Labor Ministry charged five Aricell officials with violations of the Serious Accident Punishment Act and laws on professional negligence resulting in death or serious injury, as well as banning them from leaving the country.

Of the 23 fatal victims in the tragedy, 18 were identified as foreign workers. Police plan to investigate whether the 18 foreign workers were illegally hired and whether there was any negligence on the part of CEO Park Soon-kwan, the company's headquarters or safety management officials.

Based on data obtained from the search and seizure, police will also check whether the company had provided fire prevention and safety training to employees, including for evacuation in the case of an emergency.

Authorities said earlier in the day that autopsies will be conducted on all 23 bodies recovered from the site to determine the cause of death. Among the 23 people -- 17 Chinese nationals, five Korean nationals and one Laotian national -- only three of the Koreans had been identified as of Wednesday morning, the Central Disaster and Safety Countermeasures Headquarters confirmed.

The remaining 20 bodies are expected to be identified by matching partial DNA collected from them with family members.

Theoretically, it takes two to three days for the DNA to be matched to confirm the identity. As all of the victims' DNA had been collected during autopsies, the identification of victims will depend on how quickly the DNA of their relatives can be obtained.

According to the city of Hwaseong's investigation and recovery center for the accident, 16 of the 18 foreign victims have family members living in Korea who can provide DNA, which will speed up the process of identification.

However, variables remain, as two victims need at least one family member to arrive from China for the identification process. How long it will take for the relatives of the two victims to arrive to South Korea and whether the collection of DNA will be successfully conducted from those still living in the country could determine the period of identification. The Ministry of Justice, Ministry of Foreign Affairs and other relevant agencies will cooperate to facilitate the entry of the bereaved families to Korea.

Meanwhile, as lithium battery fires are notoriously dangerous and difficult to extinguish, voices calling for preventive measures have increased, leading the government to conduct urgent inspections on similar battery plants.

It took only 42 seconds for the first battery to explode and fill the room with smoke.

Security camera footage showed workers tried to control the flames with a powder extinguisher 12 seconds after the initial explosion. But the smoke did not abate, and consecutive explosions followed. By 10:30 a.m., black smoke filled the room, leaving the security footage inscrutable.

The cylindrical batteries are believed to have exploded for unknown reasons, causing the combustion to spread rapidly and resulting in multiple fatalities, fire authorities explained. All 23 bodies of the deceased were found on the second floor, where the fire initially started.

Lithium batteries are widely used in smartphones, laptops, electric vehicles and military equipment. While these batteries are generally safe during normal use, they pose fire risks when overcharged, short-circuited or damaged, as they are sensitive to high temperatures and inherently flammable. Once lithium batteries catch fire, it is hard to put out, causing considerable damage, as seen in the tragic Aricell factory fire.

As such accidents could be prevented with the right measures in place, the government ordered more than 500 battery manufacturing workplaces to conduct emergency self-inspections based on a lithium handling safety checklist on Wednesday. In addition, fire authorities are conducting urgent fire safety investigations with relevant ministries for more than 200 battery-related companies.