An estranged husband has been arrested on suspicion of murder after a mother and her daughter were found stabbed in different locations in east London.
The body of a woman, in her 40s, was found with her throat cut in Stansfeld Road in Beckton at about 0730 BST.
Inquiries led to a house in Leamouth Road, East Ham, which was on fire. The body of the second woman, in her late 60s or 70s, was on the ground floor.
The man, the ex-husband of the younger victim, was found wounded in the loft.
He was taken to a hospital for treatment to a slashed neck.
The man, in his 40s, is not thought to have life-threatening injuries. His wounds were believed to be self-inflicted.
A Metropolitan Police spokesman said officers were trying to identify the women and trace their next of kin.
Det Ch Insp Phil Rickells added: "The elderly lady had been staying with her daughter after arriving in the UK three months ago.
"This was a horrific attack in broad daylight."
Post-mortem tests are due to be held on Friday morning.
Both the women and the man are from eastern Europe.
An emergency call from a passer-by alerted officers about the younger woman, who was found in the street close to the junction with Jasper Road.
She was attacked at a bus stop on her way to work.
Michael Herbert, 47, witnessed the aftermath.
He said: "I heard screaming and went around the side of the building.
"The guy was standing over the body with a knife in his hand and a woman was lying on the ground cut open. It was not a very nice scene to see.
"He started running away from the scene, so two of us made chase."
Describing the moment he caught up with the knifeman, Mr Herbert continued: "He threatened us, saying, 'keep away, I've got a knife'."
Paramedics failed to resuscitate the woman and she was declared dead at the scene.
Ben Tilley, 28, who lives nearby, said: "When they first moved here they were a nice couple, a pleasant couple.
"They were very house proud. Something happened a year ago and he moved out."
He added: "I saw him taken from the property by paramedics."
The younger victim's mother had moved into the Leamouth Road house after the couple separated.
A spokesman for London Fire Brigade said they were called to the fire in one of the bedrooms at the property at 0740 BST. He said it took firefighters 35 minutes to bring the fire under control.
The first floor was badly damaged by the fire and smoke. Paramedics were called to the scene at 0800 BST.
The fire is thought to have been started deliberately.