The collapse of the Royal Plaza Hotel occurred on 13 August 1993, in the city of Nakhon Ratchasima (also known as Korat), Thailand, killing 137 people and injuring 227.  At around 10:10 am, the six-story building totally collapsed in less than ten seconds due to structural failure. Several people were rescued from the rubble and trapped victims called for help through mobile phones. At the time of the collapse, about 200 people were attending meetings, one for provincial teachers and a meeting for employees of the Shell (Thailand) Company. Subsequent investigations found the disaster to have been due to the addition of three floors to the original three-storey structure in 1990, which resulted in the building's structural factor of safety being reduced to nearly one. Gradual deformation due to creep weakened all the ground floor support columns and when one failed the rest rapidly followed, resulting in an almost complete vertical collapse. Violation of safety regulations and unprofessional approach on the part of the engineer were deemed to be the cause of the disaster. Police arrested the owner of the building and five others to frame charges. Rescue operations continued for more than 20 days, upto 3rd September 1993.