HARTFORD, Conn. -- The work week opened with a white-knuckle ride Monday in the snow-clobbered Northeast as drivers encountered unplowed streets, two-lane roads reduced to a single channel and snowbanks so high it was impossible see around corners.

Schools remained closed across much of New England and New York, and more than 80,000 homes and businesses were still waiting for the electricity to come back on after the epic storm swept through on Friday and Saturday with 1 to 3 feet of snow that entombed cars and sealed up driveways.

The storm was blamed for at least 18 deaths in the U.S. and Canada, and officials warned of a new danger as rain and higher temperatures set in: roof collapses.

In hard-hit Connecticut, where some places were buried in more than 3 feet of snow, the National Guard used heavy equipment to clear roads in the state's three biggest cities.

"This is awful," said Fernando Colon, of South Windsor, Conn., who was driving to work at Bradley International Airport near Hartford on a two-lane highway that was down to one lane because of high snowbanks.

Most major highways were cleared by Monday, but the volume of snow was just too much to handle on many secondary roads. A mix of sleet and rain also created new headaches. A 10-mile stretch of Interstate 91 just north of Hartford to Massachusetts was closed briefly because of ice and accidents.

In New York, where hundreds of cars became stuck on the Long Island Expressway on Friday night and early Saturday morning, some motorists vented their anger at Gov. Andrew Cuomo for not acting more quickly to shut down major roads, as other governors did, and for not plowing more aggressively.

"There were cars scattered all over the place. They should have just told people in the morning, ‘Don't bother going in because we're going to close the roads by 3 o'clock.' I think Boston and Connecticut had the right idea telling everybody to stay off the roads and we got a better chance of clearing it up," said George Kiriakos, an investment consultant from Bohemia, N.Y.

On Monday morning, he said, conditions were still miserable: "It's just as slick as can be. You've got cars stuck all over like it's an obstacle course."

Cuomo has defended his handling of the crisis and said that more than one-third of all the state's snow-removal equipment had been sent to the area. He said he also wanted to allow people the chance to get home from work.

The number of homes and businesses without power was down from a peak at 650,000. More than 70,000 of those still waiting were in Massachusetts.

Flights resumed at major airports in the region. Boston's transit system resumed full service Monday but told commuters to expect delays. The Metro-North Railroad was mostly up and running in suburban New York City, while the Long Island Rail Road said riders could expect a nearly normal schedule.

Connecticut Gov. Dannel P. Malloy said there have been about six roof collapses involving barns and other structures.

Officials said people should try to clear flat or gently sloped roofs to relieve the weight -- but only if they can do so safely.

One of the biggest malls on Long Island was evacuated because of major roof leaks after a rainstorm followed nearly 3 feet of snow, police said.

The Smith Haven Mall in Suffolk County was cleared by 4 p.m. Monday after significant leaks were detected in more than a dozen stores. Police worried the roof could collapse.