An accountant is thought to have returned home to find his wife had murdered their two young sons before killing herself in her family home.
The 33-year-old mother and her two boys - a five-year-old and his seven-month-old baby brother - were found dead in the family home in Harrow, north-west London.
Neighbours said that a Sri Lankan mother, who has an accountant husband, lived in the two-bedroom first floor maisonette.
Murder investigation: Police stand guard outside the property in Harrow, north-west London, this afternoon as a probe gets underway
Probe: Officers were called to the property in north-west London at 5pm yesterday evening. A woman and her two sons were found dead
All three people were discovered dead last night after police officers entered the property at 5.20pm.
An elderly man who lives near the house said a family had only recently moved in to the address.
Peter Wood said police were standing guard outside the property in Woodgrange Close, Harrow, but he had never spoken to the victims.
He said: 'They have not been here long and I have never even spoken to them.