The first four floors of the establishment were gutted in the late-morning blast that sent debris flying, smoke billowing into the air and rubble tumbling to the ground.
The explosion tore off large parts of the facade, blew out windows and destroyed cars parked outside the hotel, known for having hosted celebrities such as Madonna, Beyonce, Mick Jagger and Rihanna.
The dome of a nearby Baptist church also collapsed.
A 29-year-old Spanish tourist, who had been walking nearby, was among the fatalities, which also included four children and a pregnant woman.
The tourist's husband was injured in the blast that an official said happened while a gas tank was being refilled by a tanker truck.
Officials from the United States, Canada, the European Union, China, Russia and Venezuela have sent messages of condolence.