A seven-story building on the verge of its grand opening abruptly tilted to one side in Asan, South Chungcheong Province on Monday morning.
The building, one of two, was scheduled to be completed at the end of this month.
No injuries were reported as no one was inside at the time.
Police have restricted access to the site and are preparing for a total collapse. Experts assume the cause was faulty groundworks or land subsidence.