PHILADELPHIA (AP) -- Pennsylvania's utility regulator said Thursday that 451,000 customers were still without power as the south-central and Philadelphia regions worked to recover from a crippling ice storm.
Power companies provided the latest figures to the Pennsylvania Utility Commission as of 11 a.m., agency spokeswoman Jennifer Kocher said. They represented a decrease in outages of about 300,000 from 24 hours earlier.
Utilities warned it may be late Friday before most customers will have their service restored after damage that Kocher likened to a hurricane.
The Northeast's second winter storm of the week dumped more than a foot of snow in some places 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 was the thick coating of ice it left on trees and power lines.
"Many of them already had a coating of snow on them," FirstEnergy spokesman Mark Durbin said. "It's that weight that crushes our equipment. Multiply that by hundreds of locations."
Pennsylvania Gov. Tom Corbett issued a disaster emergency proclamation, freeing up state agencies to use all available resources and personnel.
About 3,500 workers from as far away as Canada and Arkansas were working with PECO, southeastern Pennsylvania's dominant utility, to restore power, company spokesman Ben Armstrong said. The repair efforts would extend into -- and possibly through -- the weekend, he said.
"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," Kocher said. "This damage is very similar to what we see during hurricanes."
The temperature dipped to about 20 degrees overnight and forecasters said it would remain chilly through the weekend, with daytime highs around freezing and overnight lows in the teens. Shelters and warming centers were established from the Philadephia area west to York and Lancaster.
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.
While some homeowners fired up generators, others, like Dave Dixon and his wife, relied on the generosity of others to power them through. They planned to stay with 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, just north of Philadelphia, Hannah Reimer took to Facebook to ask for a kerosene heater and recommendations on where to buy the fuel.
"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."
In neighboring Maryland, where 76,000 customers were in the dark, power companies gave a restoration estimate of Friday. More than 5,000 New Jersey customers also lacked electricity.
The storm was the second-worst in PECO's history -- eclipsed only by the nearly 1.8 million that were left without power after Superstorm Sandy in 2012 -- with the utility reporting 623,000 outages at one point Wednesday.
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.
Associated Press writers Marc Levy and Mark Scolforo in Harrisburg, Kevin Begos in Pittsburgh, and Ron Todt, Maryclaire Dale and Matt Moore in Philadelphia contributed to this report.