Avon and Somerset Police were called to Sterncourt Road, Bristol, at about 06:30 BST and declared a major incident, evacuating nearby residents to a temporary rest centre.
Police said the area was cordoned off as a precaution, with no significant damage believed to have been caused to other properties.
The force said it was not treating the blast as suspected terrorism despite the recent UK threat-level change, and officers were also making inquiries at a linked property in Speedwell.
With terrorism ruled out and no suspects sought, what really happened inside the Bristol house?
Could the Bristol explosion mirror the Derby case of deliberate destruction for personal reasons?