MANX Gas has issued emergency information as 750 customers in Colby and Castletown have lost their gas supply.
The information applies to all mains gas users in the Castletown and Colby Towns gas area only and does not affect LPG customers.
A spokesman said: "There is a major problem with the gas supply. We have turned off the gas supply in your area.
"This action is being taken for safety reasons. We need you to turn off your gas now to enable us to begin the restoration of supplies.
"We are taking this unusual action because of a gas supply problem. The problem is expected to last for two days.
"All Towns Gas (NOT LPG) users in the Castletown and Colby areas are affected.
"There will be no gas for anyone to use – individuals, homes, businesses are all affected.
"Please be a good neighbour and pass this information on to your friends, neighbours and relatives.
"We will make every effort to get the gas back on again quickly.
"You must turn off your gas appliances and equipment now.
"If you are able, please turn off your gas supply at the meter – this will enable the gas to be reconnected more quickly when it is safe to do so.
"Do not use gas until you have been told it is safe, by a Manx Gas service engineer or Gas Safe registered engineer.
"You will be told when it is safe to turn your gas on again.
"We will be working with the local authority to identify people who need special help. Please be a good neighbour and check on those you know who are elderly or infirm.
"We have established a help centre at the Castletown Commissioners Office and a Manx Gas representative is attending at Station Park Colby.
"Please call 644444 if there is anything you need or if you have a friend relative or neighbour who has any special requirements.
"Please tune into the local radio for the latest news.
"We are working hard to try and return the situation to normal as quickly as possible.
Your safety is our top priority."
More than 20 engineers are working on the problem.
Manx Gas' acting managing director Robert Gardner said: "I regret that our customers in Castletown and Colby have been affected by this incident which has occured as a result of a technical plant failure in the Port St Mary plant. I have put in place all the necessary actions to restore supplies to both areas as quickly as possible."
