2 people stabbed to death 40 minutes apart in London

What we know so far:

A man in his 20s was attacked with a knife in Zenith Close, Colindale, north London, just before 6pm on Sunday. Land and air ambulance crews treated him and he was taken to hospital in central London, but he died later in the evening.

A woman, also in her 20s, who knew the victim, has been arrested on suspicion of murder.

About 40 minutes later, a woman in her 30s was stabbed to death in Brixton, south London. The victim was found on Sudbourne Road.

She was pronounced dead at the scene despite the efforts of emergency services. A man was arrested on suspicion of murder and is in custody at a south London police station; investigations are continuing.

The pair are thought to have known each other, and the victim's next of kin have been informed. Formal identification of the woman has not yet been completed.

London's air ambulance attended the incident and officers from the Metropolitan police homicide and major crime command have been informed.  

In the separate attack on Alexandra Palace Wa, Haringey, a 19-year-old man was arrested near to the scene on suspicion of affray.

He was taken into custody at a north London police station.