A 15-year-old boy was arrested on Tuesday evening in connection with an arson attack on a house in Co Tyrone.
The teenager is being questioned on suspicion of arson with intent to endanger life following the attack on the house in Dungannon on Monday.
A 70-year-old woman and man aged 37 remain in a serious condition in hospital while two children, aged seven and 10, are in stable following the arson attack on the Cunninghams Lane home, which happened around 8.30pm.
“A 15-year-old male has been arrested on suspicion of arson with intent to endanger life, and remains in police custody at this time, assisting with enquiries,” a PSNI spokesperson said.
“A police cordon remains in place as officers work alongside the Fire Service to establish the cause of the fire.”
Eight police officers have been hailed for their bravery after rescuing two adults and two children from a burning house in Co Tyrone after it was set alight.
The PSNI said officers used ladders from neighbouring properties to enter the house on Cunninghams Lane in Dungannon on Monday night after responding to a report of children trapped in the house.
Speaking on Tuesday afternoon, Deputy Chief Constable Bobby Singleton said the blaze had been started deliberately, as he praised the officers for their bravery, adding if not for their actions, lives would have been lost.
A 21-year-old man is still being questioned by police on suspicion of arson after being found on the roof of the house.
It came as the landlord of the property told The Irish News that the family living in the property were “good people”.
Abdul Alim said he rushed to the scene on Monday night after receiving a phone call from a neighbour to tell him the house was on fire.
“It was awful, terrifying,” he said.
“They are tenants of mine, they have lived here for a long time, they are good tenants, they are good people.”
The family, who are originally from Portugal, were in the property when the fire was started around 8.30pm with neighbours telling of how they heard “roaring and shouting” from the scene.
Video footage shared on social media showed a screaming child at an upstairs window as the front door is engulfed in flames.
Police said on Tuesday that two people were in a critical condition in hospital following the blaze.
Officers rescued a man aged 37 and 70-year-old woman along with two children, aged seven and 10, from the property. The children are in a stable condition.
Eight police officers were treated for the effects of smoke inhalation, but were later discharged from hospital.
Mr Singleton confirmed on Tuesday that the the fire had been started deliberately, adding that police were not currently treating the incident as a hate crime.
“Police were the first emergency responders to arrive on the scene and when they did arrive the house was already well alight,” he told a press conference in Belfast.
“Our officers obtained two ladders from neighbouring properties and were able to rescue an unresponsive 70-year-old woman and a young child from the rear of the property.
“A number of the officers then very bravely entered the house and brought the second child and a 37-year-old to safety.
“The adults remain in a critical condition in hospital whilst the children, thankfully, as we understand it, are presently in a stable condition.
“We can confirm that this fire was started deliberately. It’s hard to comprehend that mindless cruelty of the kind of this act and the panic and fear it caused to those in the home is absolutely unimaginable.”

Mr Singleton said eight officers were also taken to hospital after the fire, as he expressed pride for the actions they took to rescue those trapped.
“I’m extremely thankful that our colleagues were released in the early hours of this morning following treatment, and although they’re still suffering from the effects from smoke inhalation and will be absent from work for a period of time, they are thankfully, all ok,” he said.
“We’re extremely proud of what our officers did at the scene last night and we want to put that on the record.
“At a time when we’re advertising police recruitment for new officers, their actions serve as a very powerful demonstration of what policing here is all about.”
A police cordon remained at the scene on Tuesday as forensic officers carried out investigations throughout the day.
Black scorch marks were visible on exterior walls of the house, with damage to the front door and a broken upstairs window, where a ladder used to help rescue those inside was still perched.
Mr Alim, who owns the property, returned to the scene on Tuesday morning to survey the damage. He had been working in his Bengali Spice restaurant in Dungannon when he said “the neighbours phoned me and I came here straight away”.
“There were lots of ambulance, police and fire brigade,” he said.
“It was awful, terrifying.
“They are tenants of mine, they have lived here for a long time, they are good tenants, they are good people.
“They are Portuguese, living here a long time, family and the children at school.”

He said he spoke to one of the family in hospital just hours after the fire.
“I rang them about 11 o’clock in hospital,” he said.
“She said to me, we are in hospital at the moment, I said ‘are you ok’ and she said ‘yes we are ok’ - that is the main thing.
“No-one is harmed, that is the main thing.”
Asked if he knew why the house had been targeted, he said: “I do not know anything, so far I do not know anything.”
Neighbour Christine Robinson said she “knew it was serious” by the sound of the numerous fire engines arriving on the street.
“I came running out and thought it was actually an accident because there were so many people and there was a lot of roaring and shouting,” she said.
“I walked up and realised the smoke was coming out of the house and I could see it was a house fire.
“Then when I was walking back I could hear something exploding or unless it was them trying to break down the window or something.
“I was standing away because the fire brigade was trying to get the people out of the house, but the people gathered here wouldn’t move back to let them out - they just wanted to take photographs and videos.”

She added: “They brought the child out the door.
“It was scary, you thought it was a car crash and the next thing it was a fire.
“As long as everybody is ok.”