Two people remained in custody after a teenager was found dead in a bath.
A post-mortem examination is expected to be carried out on a 15-year-old boy who was discovered apparently drowned and with a number of other injuries in Newham, east London on Christmas Day.
Scotland Yard said a 27-year-old man and a 27-year-old woman had been arrested and remained in custody.
Police were called by London Ambulance Service to an address in Hathaway Crescent at 12.15pm on Saturday following reports of a drowning.
The boy was pronounced dead at the scene. Next of kin are aware, a Yard spokesman said. The death is being treated as suspicious.
Members of the Metropolitan Police's Homicide and Serious Crime Command are investigating.
The two people arrested are in custody at separate police stations in east London.
A Newham Council spokesman confirmed that the boy was not known to them.
Police said four other children were found at the address. Two had gone to hospital for treatment, and had been discharged.
All four are under police protection, a Yard spokesman said.