Two boys aged five and two are in a "critical but stable" condition following the explosion at a Seven Sisters property.
A 31-year-old woman, believed to be their mother, is also in a "critical but stable" condition. All three patients remain in hospital.
Emergency services were called to reports of an explosion at the property in Neath Port Talbot at around at 2.05pm on Wednesday, June 24.
On the day, police confirmed two children were taken by air ambulance to Southmead Hospital, Bristol and one adult was taken by road ambulance to Morriston Hospital in Swansea.
Church Road remains closed on Thursday, June 25 and people are being told to avoid the area.
There is still a high emergency service presence.
Around 14 properties were evacuated and Neath Port Talbot Council opened a rest centre with support for these residents.
An investigation into the cause of the explosion is underway.
A spokeswoman for the force said: "South Wales Police can confirm the three people injured in the incident yesterday (June 24), a 31-year-old woman and two boys aged two and five all remain in hospital and are in critical but stable conditions.
"The road remains closed and we continue to ask people to avoid the area.
"The cause of the explosion is under investigation."
Sarah Burgess, Wales and West Utilities gas emergency service manager for Neath said:
“We were called yesterday to reports of an explosion at a property in the Church Road area of Seven Sisters (June, 24) and immediately sent a team of emergency engineers to the scene.
“We worked with the emergency services to make the site safe. We do not operate the gas network on Church Road and have handed it over to the relevant independent gas network to continue the investigation.”
