SEOUL, South Korea (AP) — A library under construction in South Korea collapsed on Thursday, leaving one worker dead and three others trapped under the rubble, officials said.

Four workers were initially buried in the collapse in the southern city of Gwangju.

One of them was pulled out but later declared dead at a nearby hospital, local emergency officer Ahn Gyun-jae told a televised briefing. Ahn said rescuers found the location of a second worker and were trying to retrieve that person.

Ahn said authorities have mobilized cranes, drones, thermal imaging cameras and rescue dogs.