Police returned fire and a 29-year-old, who it is reported was under surveillance, was fatally shot.
The extent of the officer’s injuries is unknown but he has since been discharged from hospital, a spokesman for the Independent Police Complaints Commission (IPCC) said.
The police watchdog says it will probe Scotland Yard’s role in the incident.
Jay Crowned, 39, who lives locally, named the victim as “Mark”, a father-of-four.
She said the man had three girls and one boy and described him as “a good daddy”.