GUMI, SOUTH KOREA (BNO NEWS) -- Five people were killed on early Saturday afternoon when a large explosion ripped through a textile factory in southeastern South Korea, local media reported.

The blast happened at around 1.35 p.m. local time in Gumi, the second largest city in Gyeongsangbuk-do province, located some 200 kilometers (124 miles) southeast of Seoul. It happened at a three-story laboratory building which is part of textile firm TK Chemical.

The Yonhap news agency reported that seven people were inside the building when the explosion happened, killing all but two of them. The two injured were taken to an area hospital with serious burns, according to the report.

It was not immediately known what caused the explosion, but police are looking into the possibility that experiments involving chemical substances may have ignited the blast.

Ten fire trucks and dozens of firefighters worked two hours to bring a resulting blaze under control.