The blaze broke out around 10.30am on the eighth floor of the tower on Soi Narathiwat Ratchanakharin 18 and spread quickly to upper storeys as firemen rushed to the scene near the Chan intersection, police said.
The fire was contained at around 1pm, with cracks visible on the structure. It has been declared a danger zone in fear of collapse due to fire damage and water innundation.
The building is the residence of the family and relatives of Vikrom Aisiri, a former Democrat MP and owner of Phuket Air. A nearby kindergaten also was evacuated.
Six fire trucks and two ladder trucks were sent to the scene. Once the blaze was out, one person was confirmed dead and five hurt, according to the Bangkok Metropolitan Administration's Erawan Centre.