Posted Tuesday, November 1, 2011 --- 7:40 a.m.

WAYLAND, Mass. (AP) -- Thousands of young trick-or-treaters will have to wait to collect their Halloween treats as communities across the Northeast postponed holiday activities while waiting for electricity to return after an early snowstorm downed trees and power lines.

More than 3 million lost power at some point over the weekend and utility companies had restored electricity to hundreds of thousands by early Tuesday. Still, companies say the storm presents an enormous challenge, in part because of a large number of individual outages.

Authorities blame the storm for at least 21 deaths, including one in Canada. Most were caused by falling trees, traffic accidents or electrocutions from downed wires.

The storm caused hundreds of schools to close along with businesses and some government agencies.

Copyright 2011. The Associated Press.