HARTFORD, Conn. — Crews worked feverishly today to restore power to nearly 1.2 million homes and businesses in the Northeast in the dark after a freak weekend snowstorm, while many schoolchildren again stayed home and some residents languished for a fourth day in shelters that provided heat and meals.

Connecticut, the hardest-hit state, still had nearly 550,000 customers without power, down from more than 800,000. Huge swaths of the state also lost power for days to the remnants of Hurricane Irene in August, and residents were growing restless.

“We understand the frustration everybody is feeling,” said Jeffrey Butler, president of Connecticut Light & Power Co., the state’s largest utility. The company was on track to fix 99 percent of the remaining outages by Sunday, he said — a full week after the storm.

Classes were canceled in many areas for a third day, including a dozen districts in northern New Jersey. Some districts worried they’d use all their anticipated snow days even before the start of winter.

The state still had 180,000 homes and businesses without power — a far cry from the 700,000 in the dark during the height of the storm Saturday. Crews reported progress elsewhere, too. Maryland utilities reported scattered outages — a total of about 330, down from more than 40,000.

More than 3 million people lost power from Maryland to Maine as leaves that had yet to drop captured wet, heavy snow — from about an inch to more than 30 in spots — and snapped branches and trees that took down power lines across the region. The storm has been blamed for at least 25 deaths, most through traffic accidents, falling trees or electrocutions from downed power lines.

Connecticut expected 110 extra line crews to arrive Thursday morning and restore power to 150,000 more homes and businesses by Thursday morning. The crews will join more than 1,000 people currently working to restore power.

Gov. Dannel P. Malloy said 92 shelters remain open across the state, 15 state roads are still closed and 135 people have been treated for carbon monoxide poisoning. The governor also said 4.2 million yards of debris needs to be removed.

Butler discounted reports that out-of-state crews were slow to come to Connecticut because some hadn’t been paid yet for helping in the aftermath of Irene. He said invoices of three companies were at issue. Two of the companies were paid Monday and the third was paid this morning, he said.

Butler also repeated previous statements that the snowstorm was much worse than what was forecast and that Connecticut Light & Power did request out-of-state crews before the storm hit.

A federal Department of Energy Department official had said Tuesday that extra crews were not in place or ready to work in Connecticut before the snowstorm like they were before Irene, because utility officials had much less time to prepare.

Malloy later said that “there’s going to be a lot of time to examine the behavior of organizations we rely on,” but his top priorities are now getting power restored and keeping people safe. State officials have already begun looking at CL&P’s response after Irene, which left 730,000 customers in the dark.