A family of four were in a serious condition in hospital on Tuesday after a suspected gas explosion destroyed their home in Ayr.
Police said a man, a woman and two boys, aged 16 and 11, were being treated in Glasgow following a major incident on Monday night in which four properties were severely damaged.
An investigation into the cause is under way, with the incident having been described as "complex". Neighbours said they had pulled members of the injured family from the rubble.
A local councillor said he understood the explosion had been caused by gas and police said that, while this had not been confirmed, it was "a line of inquiry".
Nearby residents in the Kincaidston area had to be evacuated, and it could be several days before they are allowed to return to their homes.
Drone footage from the scene showed devastation, with debris strewn across the street.
Chris McNicol, 40, said he had helped pull a boy from the rubble following the explosion after running to the scene.
"I just got my trainers on and ran up to see what was happening," he told the BBC. "It is something you are never, ever going to forget.
"It was instinct to run in and try and help. When I got in, there was a kid with his leg trapped. There were two guys trying to help the kid. I just helped a wee bit as well, just to steady him a bit."
Emergency services took over the rescue efforts after the explosion, which happened shortly after 7pm. Nine appliances, as well as urban search and rescue teams, responded.
Chris Cullen, a local SNP councillor, said the incident had been caused by gas. "It is quite harrowing actually,” he said. "Early [on Monday] evening there was a row of houses, and now there is a hole."
He said that if gas from the affected properties could not be capped, residents may not be able to return for up to 10 days.
South Ayrshire Council asked members of the public to stop bringing donations to a school to which some evacuated residents were initially taken, such was the scale of the response. People unable to stay with friends or relatives are being put up in hotels.
Witnesses described the air being filled with black smoke and a bang that could be heard for miles.
A 43-year-old woman and the 16-year-old boy were being treated at Glasgow Royal Infirmary. A 47-year-old man was admitted to the city's Queen Elizabeth University Hospital, with the 11-year-old boy at the Royal Hospital for Children.
A council spokesman said: "Once we know who may still require accommodation, our housing teams will work with residents to support them.
"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."