Four children found at an address where a 15-year-old boy was discovered dead in a bath are under police protection, officers said.
Two of the youths found at the flat went to hospital for treatment and were discharged, the Metropolitan Police said.
A man and a woman, both aged 27, remain in police custody following the death of the badly-injured teenager at a flat in Newham, east London, on Christmas Day.
Results of a post-mortem examination are expected soon.
Police were called by London Ambulance Service to an address in Hathaway Crescent at 12.15pm on Christmas Day following reports of a drowning.
The boy was pronounced dead at the scene and his death is being treated as suspicious.
Members of the Metropolitan Police's Homicide and Serious Crime Command are investigating.
A Newham Council spokesman said the boy was not known to the authority.
