A police officer has been stabbed in the head after confronting a man who took hold of a baby.
A man, 20, has been arrested on suspicion of attempted murder and is in custody at a south London police station.
Officers attended an address in Walworth, south-east London shortly after 8pm following reports that a man, armed with a knife, had picked up a baby.
The man put the baby down when police arrived at the scene but attacked the officers present, stabbing a male Pc in his thirties in the shoulder and head. The officer was taken to hospital, but later discharged.
A Scotland Yard spokesman said: "Officers attended the address and attempted to speak to the man. The man put the baby down but subsequently attacked the officers present."
The Metropolitan Police have launched an investigation into the stabbing.