A man has been charged with the murder of a one-year-old boy and the attempted murder of a girl believed to be the child's twin.
Bidhya Sagar Das, 33, was wanted by police in connection with a "domestic incident" at a flat in Wilberforce Road, near Finsbury Park, north London, on Saturday night.
Both toddlers were discovered with critical injuries at the address and were taken to an east London hospital, where the boy died in the early hours of Sunday morning.
Das, of Wilberforce Road, was charged in the early hours of Tuesday and is due to appear in custody at Thames Magistrates' Court later.
The girl, who has been operated on, remains in hospital in a critical condition, police said.
A post-mortem examination in relation to the boy, who has not been formally identified, will take place later on Tuesday at a central London hospital.
Witnesses heard a woman shouting for help on the street outside at around 11.10pm on Saturday and later saw two children being carried out of the property.
Mihai Manea, 29, who lives on the second floor of the white three-storey building, said the children were twins and lived on the top floor with their Romanian mother and Indian father.
A woman living opposite the building, who gave her name as Gui Gui, said she opened the window to offer help after hearing a woman shouting: "My kids."
Das was arrested in the Hackney area at 7.15pm on Sunday following a major search by police.