Three days after Hurricane Sandy knocked out power to hundreds of thousands of Massachusetts residents, utilities remained confident that electricity would be restored to all but a few isolated households by early Friday.

Once power is back on locally, the companies plan to dispatch crews to areas that sustained severe devastation, including New York, New Jersey, Rhode Island, and Connecticut. One company, Unitil of Hampton, N.H., has already sent gas and electric crews to New Jersey and Rhode Island, according to a spokesman.