A spokeswoman for London Ambulance Service said: "We were called just before 12.40 today to reports of an incident in Eltham High Street, and sent one crew.
"Our staff treated a baby boy who had been taken unwell, who was taken to Queen Elizabeth Hospital, Woolwich."
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The boy was attacked on a bus in south London. Police say he was stabbed in the stomach.
The ComRes survey for ITV News and LBC showed the Labour candidate increasing his overall lead over Conservative rival Zac Goldsmith.
The latest poll for ITV London and LBC shows Sadiq Khan leads Zac Goldsmith by 45% to 36% on first preference votes.