Police are appealing for information on two men seen running away from the scene of the shooting on Hindrey Road, towards the nearby Pembury Estate.
One is black, officers said, while the second is light-skinned, possibly of Asian or Turkish appearance.
Police said there was as yet no clear motive for the shootings, and no-one has been arrested.
"At this very early stage we must retain an open mind regarding the circumstances of the incident and any motive," the spokesman said.
More top news
A woman hit by police gunfire during a counter-terrorism operation has been arrested after being released from hospital.
Police have been granted extra time to question a man who is being held on suspicion of planning a terror attack.
Joshua beat the older, more experienced boxer in front of 90,000 fans in Wembley Stadium.