Public liability insurance holders have been told that a suspected gas leak explosion felt like a bomb going off.
The blast, which reduced a block of flats in Shrewsbury to rubble over the New Year weekend, has left two people seriously injured and ten others hurt.
Pamela Salter, 62, whose flat overlooks the building, said that there was a huge noise and vibration, with the building and window panes shaking.
“I think we all thought it was a bomb. We looked out of the window and saw a plume of rubble rising in the air. It was incredible - and that was before the smoke and fire,” she added.
According to the source, five people who were in a car outside the building had to be pulled free after they were trapped by rubble.
A fire service spokesperson told public liability insurance holders that there had been "quite a significant gas leak", with investigations still pending into the incident.
In December, CNH (UK) was fined £25,000 after an engineer was nearly suffocated by a gas leak in one of its laboratories.