A shed was gutted in a fire behind All Saints Church, in Hanworth, during rush hour on Friday (February 13).
Four fire engines with 21 firefighters from Heston, Twickenham and Southall tackled the blaze, in Uxbridge Road, just after 5.40pm.
A 25m hazard zone was put in place and the area was cordoned off while firefighters dealt with preventing a gas cylinder from exploding.
A London Fire Brigade spokeswoman said: "We were called at 5.42pm to a fire in a shed at the rear of the church on Uxbridge Road.
"We sent four fire engines and 21 firefighters.
"A single-storey shed was completely damaged by the fire.
"There were no reported injuries.
"There was one propane cylinder which firefighters cooled to ambient temperature."
All Saints Church warden Cheryl Chisnall said no one was injured but told getwestlondon the fire had cracked a pane of glass in one of the windows.
Police said the A312 Uxbridge Road was closed in both directions - at the junction with Hounslow Road, Hanworth, and the junction of Browell's Lane, Feltham - with queues stretching back to Apex Corner.
A spokeswoman for London Ambulance Service added: “We were called at 6.03pm on Friday to Uxbridge Road to reports of a fire.
"We sent an ambulance crew and our hazardous area response team, however, there were no patients.”
Long delays were reported in the surrounding areas and a number of buses were diverted.
The fire was under control by 8.10pm. All roads were fully re-opened just after 10pm.