A collapsed valve has cut gas supplies to around 740 homes and businesses in Castletown and Colby.
Customers are being urged to turn off all gas appliances and equipment.
That's users of mains or 'towns' gas - NOT LPG.
Manx Gas says a valve at the local production plant has collapsed, which has to be fixed before supplies to local residents can be restored.
Teams of engineers are visiting all properties known to be affected.
Manx Gas hopes to begin restoring supplies by the morning.
Acting Managing Director Robert Gardner says help is at hand for those left without cooking facilities or hot water:
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