A brother and sister allegedly killed by their father were named by police tonight.
Theo Molemohi, two, and his four-year-old sister, Yolande, were found unconscious at their Manchester home by their mother at around 8am today.
Their 37-year-old father has been arrested on suspicion of murder and is being questioned by police.
The children's mother was named by police sources as Morongoe Molemohi.
Post-mortem examinations are currently being carried out on the two children.
Police said the children's father was with them when they were found. It is believed they had been strangled.
Detective Superintendent Geoff Wessell, of Greater Manchester Police (GMP), said the parents were recently estranged.
He said the children spent the weekend with their father, and their mother had gone to the flat to pick up some of her belongings when she discovered their bodies.
Mr Wessell said: "They were found in a bedroom with the father there next to them. He lived at the address. His ex-partner recently moved out and had agreed to let the father look after the children for the weekend.
"She had gone back for clothes and let herself in and was confronted by this traumatic scene."
Mr Wessell said detectives were not seeking anyone else in connection with the deaths.
The family lived in Lansbury House, a three-storey housing association block of flats in leafy Whalley Road in Whalley Range, a suburb close to the city centre.
Mr Wessell said: "This was a traumatic incident for the family and the officers that attended. No other person is being sought in connection and that male arrested remains in custody and is due to be interviewed."
He revealed that, after his arrest, the children's father collapsed and was taken to hospital. He will be questioned by police tonight.
He said the children's mother, believed to be studying for a PhD, was "extremely distressed" and is being comforted by specialist family liaison officers.
Mr Wessell said he believed the family came from either South Africa or Zimbabwe, and said they had lived in England for six years.
Neighbours spoke of their shock and described the children as "happy and well cared-for". Yolande had recently started at a local school.
Sophie Partington, 34, a resident of Lansbury House, said: "They were just a normal happy family, the kids were always playing out on the grass outside.
"I'm shocked, I just can't believe it. I can't understand what's happened. The kids were lovely, cute little kids. He was finding his feet and she was starting school.
"She was a lovely little girl with a brand new school uniform, she looked really smart, and I thought 'They must be really proud'."
Ms Partington added: "The kids seemed really happy and well cared-for. I can't understand how something like this could happen."
A neighbour, who did not wish to be named, described seeing the father being led away from the flats in handcuffs this morning.
The woman described hearing "terrible noises" before the arrest.
She said: "I had the door open and I heard this noise... it sounded like a child gasping and I heard a noise of the most horrible moaning.
"I've never heard a noise like it. It sounded like an animal."
Unemployed neighbour Mussi Gebremariam, 32, who lives opposite the family, said: "They were always playing with their mother around the garden, especially at weekends, she always keeps the door open.
"I saw the children running around a lot, they looked happy and I'm shocked to hear that this has happened."