A 14-year-old girl is among three teenagers arrested on suspicion of possessing a firearm after a police officer was threatened.
The teenagers - including two 17-year-old boys - were arrested after one of the boys allegedly pointed a firearm at an officer who stopped a youth in Lewisham, south London, Scotland Yard said.
Two male officers on routine patrol sought to stop a man in Longbridge Way at just before 8.15pm on Saturday.
Police said the 17-year-old boy pointed a firearm directly at the head of one of the officers before making off on foot.
He was later found near Lewisham Park having attempted to alter his appearance by changing his clothing, it is claimed.
The teenager was arrested along with another 17-year-old boy and a 14-year-old girl on suspicion of possession of a firearm.
All three remain in custody at a south London police station.
The officers were not injured in the incident, and the weapon was recovered by police to be examined by specialist officers.