Two women, aged 38 and 24, have died and a man and a teenage boy suffered serious injuries following reports of a stabbing in Bletchley, Milton Keynes, on Christmas Day, Thames Valley Police said.
A 49-year-old man from Milton Keynes was arrested on suspicion of murder and attempted murder and remains in police custody, Thames Valley Police said.
Officers were called to a block of apartments in Santa Cruz Avenue at just after 6.30pm. The two women died at the scene, while the man and teenage boy are in a stable condition in hospital. A dog also injured in the incident was taken to vets but did not survive.