An explosion at a nursing home in Fleetwood could have been caused by petrol vapour catching fire, say investigators.
The blast rocked Fleetwood Nursing Home in Grange Road on Saturday, March 2 at around 3.20pm.
The mysterious blast, reportedly heard as far away as Morecambe and Knott End, was initially thought to have been caused by a gas canister exploding in the grounds.
An air ambulance carrying senior clinicians was dispatched to the scene at 3.24pm, accompanied by a hazardous area response team.
But the North West Air Ambulance Service confirmed that there were no casualties and nobody required hospital treatment.
The sudden blast shattered windows and is believed to have caused some structural damage to the building.
Police confirmed to the Blackpool Gazette that the cause is still being treated as unexplained and remains under investigation.
But firefighters have revealed that the explosion could have been caused by petrol vapour catching fire inside a nearby maintenance shed.
A spokesman for Lancashire Fire and Rescue Service said: "It now appears that the explosion was not due to a gas cylinder but was petrol vapour exploding.
"The full circumstances are yet to be established but originating within a shed on site."
But investigators said the cause is still to be confirmed and remains under investigation.
The spokesman added: "Early indications of the cause of the explosion are unconfirmed and the circumstances and cause are under investigation."
On Sunday (March 3), police confirmed that a local man had been interviewed and is assisting with their enquiries.
He has not been arrested.
Police have also ruled out foul play and confirmed that the incident is not thought to be terror related.
Police are continuing to appeal for information that might help their investigation.
DI James Edmonds, of West Police, said: “We are in the early stages of an investigation into the circumstances of Saturday's incident.
"We are still working with our partners in the fire service to establish the exact cause of the explosion.
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"I would appeal to anyone who may be able to assist our enquiries to get in touch.
"This was a very serious incident which could have had catastrophic consequences for anyone who was in close proximity to the blast.
"Fortunately no-one was seriously injured”.
Fire crews from Bispham, Blackpool, Bamber Bridge and Fleetwood were called to the scene and an air ambulance landed nearby.
A Lancashire Fire and Rescue spokesman said: "There is still work to be done to assess potential structural damage resulting from the explosion and firefighters are assisting medical staff in transferring residents away from the part of the premises affected."
Grange Road was closed for several hours, and bus services including the number 1 and 14 services were diverted.
Anyone with information should contact police on 101 quoting log number 0973 of Saturday, March 2 or independent charity Crimestoppers on 0800 555 111.