A major department store in the heart of Seoul was forced to evacuate its customers on Tuesday after an online post alleged the installation of an explosive device inside the building.

At around 12:40 p.m., a posting was uploaded on an internet community by someone claiming to have installed an explosive on the ground level of Shinsegae's main department store in Seoul's Myeongdong area.

Authorities received a related report at around 1:40 p.m., prompting deployment of a police SWAT team and firefighters to conduct a search.

Department store employees and some four-thousand customers were instructed to evacuate the building.

The police confirmed there were no explosives after about two and a half hours, and the department store resumed its business.

Investigators are in the process of tracking down the writer of the post through their Internet Protocol(IP) address.