Detectives are investigating the murder of a 15-year-old girl which occurred in Tseung Kwan O.

Police believe the girl's 41-year-old mother killed her before leaping to her own death from their flat window.

The girl's 47-year-old father returned to their Tsui Lam Estate flat at 6.30pm and found the door locked with no response from inside. He broke into the flat and found the girl unconscious and called Police.

Officers found a note believed to be written by the woman which said she killed her daughter and would commit suicide.