An explosion at a house which left a man seriously hurt may not have been caused by gas, investigators have said.
Homes were evacuated following the blast on Lower Church Street, Chepstow, Monmouthshire at about 18:30 BST on Monday.
Wales and West Utilities said it worked with the emergency services to make the area safe.
The cause is still being looked at but the company said it was “not thought” to be linked to the mains gas network.
Gwent Police said the man, who was inside the house, was taken to Morriston Hospital in Swansea.
Richie Jones, Wales and West Utilities gas emergency service manager for Chepstow, said: “We were called to reports of an explosion at a property in the Lower Church Street area of Chepstow yesterday 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 worked with the emergency services to make the area safe and have now left the area. The cause of the explosion is still being investigated, however it is not thought to be related to the mains gas network.”
The Welsh Ambulance Service said an air ambulance, two rapid response vehicles, an emergency ambulance and the hazardous area response team had also been sent to the scene.
A cordon remains in place, with police advising people to stay away from the area.
Ben Powell, who lives opposite the blast site, said he heard “a massive bang” that “shook” his flat.
“I looked out my window and there were literally bits of the house opposite everywhere and people were screaming,” he said.
“The house looked like a bomb had gone off inside but then there was a little flame – and within two minutes the whole house had caught fire.
“It’s dreadful. I just hope everyone is OK.”