Boston (CNN) -- Widespread power outages and transit delays marked the start of a challenging week for millions of residents of the Northeastern United States, where a freak October snowstorm dropped more than 2 feet of snow in some places. Close to 1.7 million customers in five states remained without power Monday evening, and officials warned it could be Friday before power is back on everywhere. Utilities throughout the region reported significant progress in restoring power, but the cold, snowy conditions and house-by-house nature of the damage was slowing work, officials said. At least 13 deaths have been blamed on the weekend storm, which prompted emergency declarations from the governors of New York, New Jersey, Connecticut and Massachusetts, and also put Halloween trick-or-treating plans in jeopardy.
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NEW: Power outages fall to about 1.7 million in five states
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Deaths attributed to storm rise to 13
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Trick-or-treat postponements spread through Northeast
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Roads could ice up again, and fallen power lines remain a risk, officials say
Four people also died in @placeholder because of the storm, police said.