A three-year-old boy, a man and a woman have died at a home in west London, and police are not looking for anyone else in connection with the deaths.
The boy and woman, aged in her 30s, were already dead when Met Police officers broke down a door at a block of flats in Brentford just before 1am on Tuesday.
A man in his 40s was found with stab wounds, but he died at the scene while being treated by paramedics. It is thought that the boy and the adults were all known to each other.
Police went to the home “following concerns for the welfare of the occupants”.
The force has referred itself to the Independent Office for Police Conduct because officers had visited the home previously “regarding concerns for the welfare of the occupants”.
One resident told of her shock on hearing the news on Tuesday.
Sheri Diba said she had lived in the building for seven years and that it is a “nice area”.
She told reporters: “I could not imagine someone is dead in this building. It’s a very nice area, very nice building, I never had any problem. I’m really shocked.”
Detectives are trying to figure out what led up to the deaths.
Post-mortem examinations are due to take place to determine the cause or causes of the deaths.
A police spokesperson said: “An investigation is underway following the deaths of three people in Brentford.
“At approximately 12.50am on Tuesday, 6 October officers forced entry to a residential address in Clayponds Lane, Brentford following concerns for the welfare of the occupants.
“Inside the address, officers discovered the bodies of a woman, believed to be aged in her 30s, and a boy, believed to be aged three-years-old.
“A man, believed aged in his 40s, was found suffering stab injuries.
“London Ambulance Service attended but he was pronounced dead at the scene.
“It is thought all three people were known to each other.
“Enquiries are underway to inform all next of kin.
“Post-mortem examinations will be scheduled for all three people in due course.
“Detectives from the Specialist Crime Command are investigating.
“At this early stage, officers are not looking for anyone else in connection with this incident.
“Enquiries into the circumstances continue.”
The spokesman added: “Due to prior police attendance at the address regarding concerns for the welfare of the occupants, the Met’s Directorate of Professional Standards have made a referral to the Independent Office for Police Conduct.
West Area BCU Commander Pete Gardner said: “This horrific incident has understandably caused enormous shock and concern among local residents and across the borough; all our thoughts are with the family and friends of those affected.
“I would like to thank our officers and paramedics from the LAS who worked tirelessly and professionally under extremely traumatic circumstances in responding to this incident.
“Our officers in the West Area Command Unit are doing everything they can to support our colleagues in Specialist Crime as we work to understand what has led to this terrible incident.
“Local residents can expect to see officers at the scene and patrolling the local area to provide reassurance, and if they have any concerns, I would urge them to speak to our officers.”