Residents were evacuated from part of the Kincaidston area in Ayr, South Ayrshire, following the blast on Monday evening which police said affected four properties.
A family of four were taken to hospital following the incident in Gorse Park, which could be heard for miles around.
A 43-year-old woman and a 16-year-old boy are being treated at Glasgow Royal Infirmary, a 47-year-old man at the city’s Queen Elizabeth University Hospital and an 11-year-old boy at the Royal Hospital for Children.
Inquiries are ongoing to establish the cause of the blast.
As of Wednesday afternoon, 35 homes in the area affected remain out of bounds due to damage caused by the explosion.
Some of the houses have varying degrees of debris on or around them and some are in close proximity to the site of the explosion.
A spokesperson at South Ayrshire Council said four of the properties within the cordon are likely to be demolished due to the damage caused.
To date, 46 properties in the area have been deemed safe enough for residents to return.
Due to the extent of the blast, properties outside the cordon were also damaged, including four which will require extensive repairs before residents can return, the council confirmed.
Other properties have been damaged by debris and some homes are not safe to access due to broken windows and debris both inside and out.
The council said its neighbourhood services groups are on site assisting emergency services in removing the wreckage from the wider area.
The teams are also working to ensure residents displaced by the incident are returned home as soon as possible.
Council leader Peter Henderson said: “I know that council teams, the emergency services and partners have been working tirelessly to help as many people as possible to return to their homes.
“This is no easy task and I am relieved that their painstaking work has allowed some families to get back home today.
“Of course, it’s still very early days and the devastation caused by this tragic event will take considerable time to rectify.
“We are committed to working alongside our communities and partners to support them through the aftermath of this terrible event.”
The council said anyone who is from a household or knows someone from a property affected by the explosion can contact 0300 123 0900 for more information.