A mother has been arrested on suspicion of murdering her two babies.
A 10-week-old boy and his 14-month-old sister were found dead after police were called to the family's home in south-west London last night.
A woman in her mid-30s was arrested at the property and is being questioned at a south London police station, Scotland Yard said.
Detectives from the force's child abuse command are leading the investigation.
Officers are investigating the possibility that the suspect was suffering from post-natal depression.
A Metropolitan Police statement said: "Inquiries are under way after the death of two children in Wandsworth.
"Police were called to an address in Killarney Road at 7.25pm on Wednesday May 9.
"The London Ambulance Service also attended but a 10-week-old boy and a 14-month-old girl were pronounced dead at the scene.
"Post-mortem examinations will take place in due course. Next of kin are aware."
Two police officers stood outside a cordon across the gate of the family's upmarket semi-detached property, which was recently sold by Savills estate agency for £1.2 million.
Forensic officers were later seen leaving the scene.