Police in Northern Ireland have named the baby boy who was killed at a house in north Belfast as Liam O'Keefe.
Another child – understood to be the boy's toddler sister – who was also stabbed in the incident at Brompton Park in Ardoyne on Tuesday remains in hospital where her condition is described as "stable", Det Chief Insp Millar from the Police Service of Northern Ireland said.
“A 29-year-old woman arrested on suspicion of murder and attempted murder has now been released from hospital and transferred to police custody for questioning,” he added.
Det Chief Insp Millar thanked the Ardoyne community for its “unwavering support and patience” as the murder and attempted murder investigations continue.
Police have confirmed they are not looking for anyone else following the arrest of the woman.
A postmortem on the boy is due to take place on Thursday.
Soft toys and flowers were left at the scene in tribute to the children on Wednesday as neighbours tried to come to terms with the tragedy.
Police were called to the house shortly after 8pm on Tuesday and discovered the injured baby and child, said Det Chief Insp Millar.
“Despite the efforts of the emergency services the baby was sadly pronounced dead at the scene,” he said.
“The other young child was taken to hospital and remains in intensive care.
“A 29-year-old woman has been arrested on suspicion of murder and attempted murder and remains in custody at this time.
“Our thoughts are with the baby’s family, who are being supported by family liaison officers.”
Det Chief Insp Millar said that while the investigation remains at any early stage, he could confirm “that at this stage we are not looking for anyone else in relation to this tragic death”.
“I would like to thank the local community for the support that they have provided and would appeal to anyone with any information that can assist our investigation to contact us,” he added.
‘Tragic’
Sinn Féin North Belfast MP John Finucane, who visited the scene on Wednesday, said it was a "tragic situation compounded by the fact that we are dealing with somebody who has died at such a young age".
“I think there is a senselessness to it, I think people find it very difficult to try to comprehend the facts as they are being relayed and the facts as they are emerging,” he said.
“It is incredibly difficult and will obviously leave a mark on those who are most impacted by it, and all we can do is rally round those who need support at this time.”
Neighbours who came to help the injured children “witnessed scenes that they shouldn’t have to witness”, said Mr Finucane, adding that the incident had a huge impact on residents of the area.
“Ardoyne is a very proud community, it is a resilient community also and I have no doubt whatsoever that they will rally around each other at this very difficult time, they will provide help and assistance for those who need it.
“I would also just stress just for people to exercise caution and sensitivity in regards to what they would post or share on social media, there is a live murder investigation and people need to be respectful of that process as well.”
The house remained sealed off as a crime scene on Wednesday evening.