CHEONGJU -- A battery factory in the southern city of Cheongju caught fire Friday, leaving one person trapped inside, firefighters said.

The fire broke out at the auto battery factory at around 3 p.m. in the city, 140 kilometers south of Seoul.

Two people were immediately rescued, but one other is believed to be trapped inside the building, firefighting authorities said.

Police initially said four people were inside the burning building with one having been rescued, but firefighters later corrected the numbers.

A total of 16 fire engines and trucks and 40 firefighters were dispatched to the scene, but rescue workers were having difficulty accessing the burning factory due to columns of black smoke engulfing the building, authorities said.

An explosion is believed to have sparked the fire, they said. (Yonhap)