Fatima Ibrahim, the wife of one of the suicide bombers set off a bomb killing her three children when police came to raid her home.
Fatima is said to be wife of the suicide bomber-- a Sri Lankan millionaire businessman-turned-Daesh terrorist Inshaf Ahmed Ibrahim.
She set off the bomb with her unborn child, as well as three young sons, when police raided the family home on Sunday night.
The agency also released another statement identifying the seven suicide bombers by their assumed combat name
The statement said three fighters it named as Abu Obeidah, Abu Baraa and Abu Moukhtar were behind the attacks on the Shangri-La, Cinnamon Grand and Kingsbury hotels.
Three other fighters it named as Abu Hamza, Abu Khalil and Abu Mohammad carried out attacks on churches in the cities of Colombo, Negombo, and Batticaloa, it said.
The seventh fighter, Abu Abdallah, killed three police officers in an attack in a Colombo suburb, it said.
One of them, Inshaf Ibrahim, a copper factory owner in his 30s, is believed to have been the mastermind of the bomb plot.
He detonated his explosive device at the busy breakfast buffet of the luxury Shangri-La hotel, a source close to the family said.
The family's Colombo home was raided by police shortly afterwards.
Mr Wijewardene said that as police arrived, the pregnant wife of one of the brothers detonated a suicide jacket, killing herself and her two children as well as three police officers.
Ilham Ibrahim openly expressed extremist ideologies and had been involved in meetings of National Tawheed Jamaath, a local Islamist group suspected of involvement in planning the attacks, according to the source close to the family.
Who are the National Tawheed Jamaath?
His entrepreneur brother, Inshaf, was outwardly more moderate in his views, and was known to be generous with donations to his staff and struggling local households, the source said.
He was married to the daughter of a wealthy jewellery manufacturer.
The brothers' father, Mohamed Ibrahim, was arrested as police investigated those behind the attacks, police said.
Mr Ibrahim, a wealthy spice trader and pillar of the business community, had six sons and three daughters. He was admired by many who knew him.
"He was famous in the area for helping the poor with food and money. It's unthinkable his children could have done that," neighbour Fathima Fazla said.
Sri Lanka's Muslim community — which accounts for 10 per cent of its population — is on edge.
Many Muslim refugees from Pakistan living near Negombo — where a church was blown up — have boarded buses to escape the threat of retaliation.
Farah Jameel, a refugee living in the area, said her family had been chased out by angry locals.
"They are hitting us," she said. "Even our landlord is not letting us live here, she is saying to get out of here and go wherever you want to go."
Muslims living near the Ibrahim family expressed their sorrow that their neighbours were involved in the terror plot.
"Not only for Muslims, the whole community, the whole of Sri Lanka, everybody is our brothers and sisters, everybody who has passed away are our brothers and sisters," said a neighbour who identified herself by her first name Taybeh.
"I have a small brother, he was very afraid, all the kids in the lane, they were very afraid, my small brother — he is not even going to the bathroom by himself.
