PHILADELPHIA (AP) - Utility crews were working feverishly to restore power to hundreds of thousands of homes and businesses in Pennsylvania and surrounding states that were still in the dark and cold on Thursday after an ice storm knocked out electricity to more than a million customers, damage one official likened to that from a hurricane.

The Northeast's second winter storm of the week dumped more than a foot of snow in some states on Wednesday, forcing schools, businesses and government offices to close, snarling air travel and sending cars and trucks sliding on slippery roads and highways - an all-too-familiar litany of misery in a winter where the storms seem to be tripping over each other.What made this one stand out - and caused all those outages - was the thick coating of ice it left on trees and power lines. While the storm has long since cleared out, its effects are expected to linger for days."People are going to have to have so me patience at this point," Gov. Tom Corbett said Wednesday, warning that an overnight refreeze could cause more problems on the roads Thursday. The governor issued a disaster emergency proclamation, freeing up state agencies to use all available resources and personnel."The damage that we are seeing in the field with the number of trees down, not only on lines but blocking roads and more, presents a number of logistical issues," Pennsylvania Public Utility Commission spokeswoman Jennifer Kocher said. "This damage is very similar to what we see during hurricanes."At its height, the storm knocked out power to nearly 849,000 customers in Pennsylvania, most of them in the counties around Philadelphia. Though sizeable, it's still less than the nearly 1.8 million that were left without power after Superstorm Sandy in 2012.PECO, southeastern Pennsylvania's dominant utility, warned it could be until the weekend before the lights come back on for all of its more  than 431,000 customers without power Thursday morning. FirstEnergy was reporting almost 49,000 customers without power, while PPL was reporting more than 20,000.In neighboring Maryland, where 76,000 customers were in the dark, power companies gave a restoration estimate of Friday. More than 7,000 New Jersey customers also lacked electricity.Officials pleaded with people not to use generators or gas grills indoors after 20 to 25 people in the Philadelphia area were taken to hospitals with carbon monoxide poisoning.Robert Kagel, deputy director for emergency management in Chester County, told WCAU-TV that some of the more seriously injured were transferred to Philadelphia hospitals for treatment.While some homeowners fired up generators, others, like Dave Dixon and his wife, are relying on the generosity of others to power them through. They planned to stay with their friends overnight Thursday - and possibly longer."If we wear out our welcome , we'll get a hotel," said Dixon, whose home in the Philadelphia suburbs went dark at 6 a.m. Wednesday.In Wyncote, a town just north of Philadelphia, Hannah Reimer took to Facebook to ask for a kerosene heater and recommendations on where to buy the fuel."And it worked! Someone from my church, who has power, has a kerosene heater and my husband is picking it up now," she said Wednesday night.Reimer and her husband then planned to pay it forward, inviting their neighbors to spend the night."Our neighbors don't have heat, either," she said. "Or a kerosene heater."Thousands of utility workers descended on the Philadelphia suburbs to get the lights back on.It was the second-worst storm in PECO's history - eclipsed only by Superstorm Sandy in 2012 - with the utility reporting 623,000 outages at one point Wednesday. "We know that this is going to take multiple days," PECO spokeswoman Cathy Engel Menendez said.About 3,500 employees an d contractors were working to restore power, while an additional 1,000 linemen from utilities as far as Chicago were expected to join the company's efforts, she said.Several hospitals were running on backup generators. Most decided to cancel elective surgeries and out-patient testing.Dr. John Kelly, chief of staff at Abington Memorial Hospital outside Philadelphia, one of the affected facilities, said critical staff needed for any emergencies would be staying overnight. He said the hospital had plenty of fuel and food.The American Red Cross opened three shelters in southeastern Pennsylvania and stood ready to open more."We've been told to be prepared for four to six days. We are gathering staff and volunteers for up to a week," spokesman Dave Schrader said.Associated Press writers Marc Levy and Mark Scolforo in Harrisburg, Kevin Begos in Pittsburgh, and Maryclaire Dale and Matt Moore in Philadelphia contributed to this report.