Police say they are not looking for anyone else in connection with the fatal stabbing of a toddler following what has been described as a horrific incident at a house near Larne on Monday morning.
The mother and another of her children, a baby, are in hospital with serious injuries after police were called to an isolated farmhouse on Bankhall Road, in the rural community of Magheramorne.
The incident is being treated as domestic. The mother has been named locally as Fiona McGowan.
Belfast Trust declined to give out details of the condition of Ms McGowan and the infant on Tuesday on request of the family.
A PSNI spokeswoman confirmed: "A woman in her 30s and a baby are currently receiving hospital treatment for injuries.
"The investigation is at an early stage and police are currently not looking for anyone else in connection with the death."
There was widespread shock in Magheramorne after the emergency services descended on the farmhouse on Monday.
One woman who knows the family said the mother is a nurse. She described the news as "shocking".
"You just wouldn't believe it," she told the Belfast Telegraph.
You don't expect something like this to happen in a quiet area like this. You normally only read this in the papersNeighbour
There was a large police presence on the Bankhall Road with neighbours saying they were "taken aback" by the scale of the operation.
The house and outbuildings are along a narrow lane high on a hillside overlooking Larne Lough, south of Larne.
A laneway to the property was sealed off by officers as white boilersuit-clad forensic experts gathered evidence.
Neighbour Rhonda Kernohan said: "I heard the sirens and the helicopter, the air ambulance, came and it landed up at the back of the farm.
"We thought it was a farm accident but when we looked out there was a lot of shouting and a lot of police, a lot of ambulances about." She added: "This is a quiet, rural, peaceful area." Another resident said the emergency services arrived in the area at around 10am.
She said police were focused on one farmhouse which had been sealed off.
She said the air ambulance appeared to have airlifted at least one person to hospital.
It is thought the residents are relatively new to the area, which has been described as a "quiet residential rural location".
It also believed the family moved into the area around a year ago.
Another woman who lives on the road said the farmhouse has been rented out.
"I believe the youngest child is a year and half and the eldest a bit older," she said.
She described the children as "beautiful and very young".
It's an awful tragedy for the family, the wider family circle and it really doesn't bear thinking about what has occurred hereDUP MP Sammy Wilson
"I've spoken to the man once, but they generally keep themselves to themselves.
"You don't expect something like this to happen in a quiet area like this. You normally only read this in the papers."
She added: "I was heading into Larne at around 10am and was met by ambulance and police vehicles coming the other way. They then closed the lane off."
Another neighbour said the woman who lived at the house was a "youngish girl".
They added: "It was very sad. We are feeling absolutely awful, so sad, it is terrible.
"The shock of it, when it happens nearly on your doorstep."
East Antrim MP Sammy Wilson, who lives close to where the tragedy unfolded, said it was "an unspeakable tragedy" for the area.
"I have spoken to police officers and they are releasing few details at present, but this has obviously been a horrific incident," the DUP MP said.
It is absolutely awful when you hear of anybody suffering in this kind of way but when young children are involved it is particularly horrificDUP MLA Gordon Lyons
"We don't know the circumstances, except that police are not looking for anyone else in connection with the tragedy.
"We have one dead child and another critically injured with what I believe are terrible injuries.
"It's an awful tragedy for the family, the wider family circle and it really doesn't bear thinking about what has occurred here.
"There will always be questions as to how and why this has happened, what prompted the events, all sorts of questions.
"It's just an utter tragedy and from what I hear the injuries were horrific and the officers at the scene have been through an awful experience in dealing with it when they arrived at the scene.
"It's a very tight community here and there's shock all around. All our thoughts are with the wider family circle."
A DUP Assembly member for the area, Gordon Lyons, said it was clear "something horrific" had happened.
"It is absolutely awful when you hear of anybody suffering in this kind of way but when young children are involved it is particularly horrific," he said.
"My thoughts and prayers and the thoughts and prayers of everybody across east Antrim will be with the family."
David Hilditch MLA said it was a "very, very sad day for the constituency".
"The circumstances leave you without words," the DUP politician said. "All our thoughts are with the family at what is a terrible time for them all."
The area around the scene remained sealed off late last night as police continued their investigation.