Police believe a 34-year-old Hong Kong woman who was found unconscious on the ground outside a building in Cheung Sha Wan had accidentally fallen to her death early on Sunday morning.

A passer-by called police after finding the woman outside 160 Cheung Sha Wan Road at 3:12am, Apple Daily reported. She  pronounced dead at Caritas Medical Center.

During the police investigation, a fire broke out in a flat where the woman had been living with her 39-year-old boyfriend.

Trace of cocaine and nine pills of depressant Erimin 5 were seized from their home.

The boyfriend was arrested for suspected drug possession after officers found 13 grams of cocaine and traces of ketamine during a body search when he returned to the flat, Wen Wei Po reported.

Preliminary police investigation suggested that the woman may have been on drugs when she accidentally fell out the window.