A guest accidentally discharged a gun as people posed for photographs in the hotel's lobby at around 7.25pm local time.
The bullet hit the floor before ricocheting into a 55-year-old woman.
Three other people – a 59-year-old man and two women, aged 38 and 45 – were struck by debris as bits of glass, marble and tiling flew around.
All four were taken to hospital, with police saying they are expected to be fine.
The 42-year-old man who had the gun was arrested.
