A heavily pregnant woman who was stabbed to death has been named as Kelly Mary Fauvrelle.
Two men have been arrested on suspicion of murdering the 26-year-old, who was pronounced dead at a house in Croydon, south London, early on Saturday.
Her baby was delivered at the scene by paramedics and is in hospital in a critical condition.
Police said a 29-year-old was in custody and a 37-year-old had been released under investigation.
Both men were arrested on Saturday. Scotland Yard said it was keeping an “open mind as to motive”.
Det Ch Insp Mick Norman described it as “a horrific incident” and said the force’s “sympathies go out to [the woman’s] devastated family”.
“At the forefront of our inquiries is understanding what exactly has led to these tragic circumstances, and we are doing everything we can to establish the facts.”
Medics fought to save the mother, who is believed to have been about eight months pregnant, after being called at about 03:30 BST.
An air ambulance, two ambulance crews and two response cars were sent to the scene by London Ambulance Service.
A cordon is in place around the whole of Raymead Avenue, Thornton Heath, where the attack happened.
Chandra Mutucumarana, who has lived in the street since 1976, said he was “utterly shocked” and neighbours were “upset for her but hopeful for the child”.
One neighbour paid tribute to the victim, describing her as a “nice girl”, while another said she believed three women lived at the house, along with a small dog.
One resident, who lives two doors down, said she heard the animal barking when she got up at about 03.30 for prayers and added she was “shocked and surprised” to hear about the attack.
Forensics teams remain at the house, where officers could be seen swabbing an alleyway running alongside the property, while police officers are on guard at the front.
A post-mortem examination is due to be held.
On Twitter, London mayor Sadiq Khan said: “Violence against women is endemic in society and devastating murders in the home, like this one, show the scale of the problem we face.
“My prayers are with this innocent child, and with the mother it has so tragically lost.”