Local authorities investigating the deadly fire Saturday at a shooting range in Busan, South Korea, have verified through DNA tests that seven of the victims were Japanese nationals.

Chief Cabinet Secretary Hirofumi Hirano said Wednesday that police contacted the Japanese Consulate General in Busan with results of the tests. Relatives of the victims have been briefed on the DNA results, he added.

Hirano said that the cause of the deadly blaze has not been determined yet, but arson has not been ruled out. The South Korean government has promised a thorough investigation.