When there are extreme temperature events such as at this time, it is recommended to let a stream of water from the faucet, which could be vulnerable to cold, flow constantly. Please make sure that this will not cause an overflow.
Frozen water pipes?
You must call a reputable plumber or Public Works to help you with this problem. Non CSA-approved equipment used to thaw pipes may produce an electric current causing a fire in your home or in those of your neighbours. Such equipment can also damage electrical insulation. This can result in a fire at a later time. There is a charge for work done on private property. If you must wait for repairs, ask a neighbour to help you by supplying water through a hose connected to one of his outlets. 
If you notice a contractor thawing pipes at a home whose owners are absent, please advise Public Works or Public Security.
Note that the City is not responsible for frozen sump pump pipes.