A suspected gas explosion which sent debris flying through the air forced a number of residents to be evacuated from their homes.
Fire crews were called to Gemma's Cafe in East Challow, on Sunday evening.
Debris scattered over a 100m (330ft) area and there was severe structural damage to the cafe and a nearby industrial unit. No-one was hurt.
The cafe owners were being investigated for operating without planning permission, it later emerged.
Vale of White Horse District Council said an enforcement case had been opened and residents of a neighbouring property had complained about the cafe, which opened in September.
A spokesperson added that the cafe owners had been invited to apply for retrospective planning consent, but none had been received.
The cause of the blast is being investigated.
A number of residents were moved out after an exclusion zone was set up but were expected to be allowed back home on Monday.
Incident commander John Nixon said: "The explosion appears to have involved a gas leak of some kind.
"The building has sustained major structural damage so crews entered the building to check for any casualties and to isolate any gas supply that was found."