Record tides from a wintry super storm combined with hours of pounding wind and rain to deal an unprecedented blow to the U.S Northeast's power grid, flooding substations and shutting New York City's financial district.

By nightfall, Consolidated Edison Inc., New York City's utility, had killed electricity in parts of downtown Manhattan and Brooklyn as seawater encroached on crucial power equipment, warning more cuts may be coming. Crews in Connecticut threw up a dike around an electrical substation serving downtown Stamford and stood ready to shut down four others should floodwaters rise by the forecast 11 feet.

"The last time we saw this threat was never," Connecticut Governor Dan Malloy said at a press conference yesterday, warning the worst seawater flooding in 70 years could have tides lapping at the base of at least one inland dam.