A 35-year-old man has been arrested on suspicion of attempted murder after allegedly trying to stab a female police officer in the stomach.
Violence broke out when police were called to a disturbance in Lynette Avenue, Clapham, on Tuesday night.
As a female officer tried to stop the suspect involved running away from the scene, it is claimed that he pulled out two knives and tried to stab her at least twice in the stomach.
She fired her Taser, and she and colleagues managed to arrest the suspect at nearby Clapham Common. The officer was unhurt and went on to finish her shift.
The incident came amid renewed debate over officer safety in the wake of a number of serious attacks, including the death of PC Andrew Harper who was mown down while responding to a suspected burglary in August.
Forces have taken different approaches to the number of officers that they will equip with Taser, and head of the National Police Chiefs Council Martin Hewitt has stressed that protection is not just about stun guns.
The body is currently carrying out a national review of officer safety. In September, the Government announced it would give forces an additional £10 million to increase the number of officers who carry a Taser.