A man has suffered multiple injuries following a suspected explosion in Chepstow.
Emergency services are at Lower Church Street and a cordon is in place.
South Wales Fire and Rescue Service was called to the incident at around 6.30pm on September 21. It has six fire engines at the scene, in addition to support vehicles.
A person has been taken to Morriston Hospital in Swansea via air ambulance. Their sex, age and condition has not been revealed.
Gwent Police said residents are being evacuated for their own safety.
A force spokesman said: "We received a report of an explosion at a property in Lower Church Street, Chepstow shortly before 6.30pm today.
"A man, who was inside the property, sustained serious injuries and has been taken to Morriston Hospital in Swansea for treatment.
"No one else has been injured.
"A number of houses in Lower Church Street have been evacuated."
A cordon is still in place in Lower Church Street as a "safety precaution" and will be for some time, police added.
"We remain at the scene with emergency service colleagues and ask the public to continue to avoid the area," said the spokesman.
Richie Jones, Wales & West Utilities gas emergency service manager for Chepstow added:“We were called to reports of an explosion at a property in the Lower Church Street area of Chepstow this evening and immediately sent a team of engineers to the scene.
“On arrival we found that the property had been damaged and emergency services were in control of the scene.
“We are working with the emergency services to make the area safe and to investigate the cause of the explosion.”
