A suspected robber was shot in the arm by police as they tried to arrest him at a supermarket.
Scotland Yard said officers were at Netto in Rye Lane, Peckham, south-east London on Saturday evening as part of a planned operation.
The man was shot as police arrested him and two others on suspicion of conspiracy to rob. He is in a stable condition in hospital.
The fourth man ran away and is still being sought.
Police said four men were seen going into the supermarket through a rear loading bay.
During the operation a fire extinguisher was sprayed into an officer's face.
He was treated in hospital and discharged later.
A police spokesman said the wounded man would be questioned after he was released from hospital.
The two other men are being questioned at a south London police station.
Officers from the Directorate of Professional Standards are investigating.
The Independent Police Complaints Commission has also been informed.