Investigations are continuing following an explosion at a housing estate in Ayr on Monday evening.
Police have confirmed a family of four were taken to hospital where they remain in a serious condition.
A woman, 43, and a boy, 16, are currently being treated at the Glasgow Royal Infirmary while a man, 47, is in the Queen Elizabeth University Hospital.
An 11-year-old boy is within the Royal Hospital for Children.
What happened to cause Ayr explosion?
The explosion happened on Gorse Park in the Kincaidston area of Ayr at around 7.10pm on Monday, October 18.
Emergency services cordoned off the area to the public and evacuated a number of houses in the area.
Residents have reported the blast could be heard for several miles in nearby Ayrshire communities.
The friend of a woman, whose house was directly opposite the blast site in Kincaidston, described the scene as “something you cannot comprehend unless you see the sheer scale of the damage”.
Moira Muir, 59, told the PA news agency: “Her lounge window was blown in and the radiator in her upstairs bathroom was blown off the wall.”
Ms Muir, who runs a holiday home rental in North Ayrshire, rushed to her friend’s aid within 30 minutes of the explosion.
She added: “The smell of smoke was quite overpowering, but the biggest shock was seeing the amount of rubble and how far it had travelled.
“I have never seen anything like it.”
Councillor Chris Cullen told BBC Good Morning Scotland he thinks gas caused the explosion.
Describing the scene, he said: “It is quite harrowing actually.
“Early yesterday evening there was a row of houses and now there is a hole.
“Two-and-a-half houses are missing. It is quite shocking how far the debris has fallen and the damage it has caused.”
Emergency response effort to help Ayr families
A major investigation and response effort has been launched with many residents being forced from their homes due to the blast.
South Ayrshire Council has said it is working with emergency services to determine which houses are safe to return to.
A spokesman said: “As soon as we are clear where the inner cordon lies, we will start the clear-up operation, which requires to be done with sensitivity due to personal effects being included among general debris.”
Chief Inspector Derrick Johnston, area commander for South Ayrshire, said: “This is a complex incident and a number of different agencies are working together to establish the full circumstances of what happened.
“Our thoughts are with the family and everyone within the local community affected by this.
“A joint investigation with the Scottish Fire and Rescue Service is being carried out.”
Nine fire engines were sent in the initial response to the scene with two remaining at 2.30pm on Tuesday.
Ian McMeekin, the fire service’s area commander, said: “This has been an extremely complex and challenging incident which significantly damaged multiple properties in the area and resulted in the evacuation of other nearby homes.
“We will remain in attendance for some time as we work with our partners to ensure the area is safe.”
Gas distribution company SGN was helping emergency services.
Earlier, police confirmed that four houses had been affected by the explosion and said two local rest centres had been set up to assist.