The second nor'easter in less than a week pounded the East Coast on Wednesday, bringing rain and sleet to New London County throughout the day before shifting to heavy snow in the evening.

The nor'easter knocked out electricity to hundreds of thousands of customers and produced "thundersnow" as it made its way up the coast, with flashes of lightning and booming thunder from the Philadelphia area to New York City. In Manchester Township, N.J., a middle school teacher was struck by lightning while holding an umbrella outside a school. She was taken to the hospital with minor injuries, The Associated Press reported. 

Here, forecasters said the storm, which strengthened off the New Jersey shore, would dump 3 to 9 inches of snow on the region by about 2 a.m. Thursday. The National Weather Service issued a winter storm warning into Thursday morning from the Philadelphia area through most of New England. Officials were urging people to stay off the roads amid treacherous travel conditions.

By Wednesday evening the wet, heavy snow was causing power outages across the region. At 8:30 p.m. 97 percent of Montville's Eversource customers were without power.

"We got a lot of trees down, wires down," Montville Fire Marshal Ray Occhialini said Wednesday from his truck at 9 p.m., by which time the percentage of homes without power had gone down to 67 percent. "There's just heavy, heavy wet snow and it's taking all the wires down. It's a mess."

Norwich Public Utilities had approximately 850 customers without power late Wednesday, the majority in the Rockwell, Warren, Broad Street areas, and Lafayette Street, Bog Meadow and Teddy lanes. Norwich officials opened the city’s emergency operations center at 9 p.m.

Gusts approached 45 mph Wednesday, but did not match the winds that whipped through New England last week, when tens of thousands of people were left without power due to uprooted trees and toppled utility poles. Gusts up to 60 mph were forecast on Cape Cod.

"We're looking in the order of 3 to 6 inches for coastal areas and 4 to 9 inches inland," said Gary Lessor, meteorologist and assistant director at The Weather Center at Western Connecticut State University in Danbury. "If you go further west, you'll have a lot more. It's been accumulating. Everything is coated in snow."

The western and northern portions of the state already had been hit with several inches of snow, but southeastern Connecticut largely was spared until about 5:30 p.m.

Still, schools in the area were shut down Wednesday.

"We lead with safety," Preston Superintendent Roy Seitsinger said. "Often, it is not about the number of inches of snow. This year has been challenging because of the intensity of some of the storms and the time of day they were predicted to hit our area."

Temperatures had dropped to the mid-30s by 5:30 p.m. Wednesday, but likely would remain above freezing, Lessor said.

"Snow may have trouble sticking to roadways," he said. "Grass surfaces is where we forecast the accumulations."

The storm unloaded snow at a rate of 2 or 3 inches an hour, with some places in New Jersey, New York and Connecticut getting well over a foot by Wednesday night. Butler, N.J., got 22 inches; Sloatsburg, N.Y., 23 inches, and Newtown, Conn., 14 inches, according to The Associated Press. But major cities along the Interstate 95 corridor saw much less.

Still, AAA's Hartford office reported on Twitter that over 600 motorists had called the agency for help in Connecticut as of 10 p.m. Wednesday. More than 2,600 flights across the Northeast — about 1,900 in the New York metro area alone — were canceled, AP reported. Amtrak canceled some train service, and commuter trains in Philadelphia and New Jersey were put on an abbreviated schedule.

About 6 p.m., Gov. Dannel Malloy announced a ban on tractor-trailer and tandem trailer travel on limited-access highways until further notice. The move would help New York manage traffic in worsening highway conditions, Malloy said.

To minimize roadway bottlenecks, Malloy sent home all nonessential state employees in staggered 15-minute intervals starting at noon. He also ordered nonessential second-shift state employees to stay home.

"We are advising that folks stay home unless absolutely critical tonight," Malloy said.

For this storm, utility crews were prepared.

"The work continues," Eversource spokesman Mitch Gross said of the utility's efforts to restore power Wednesday. "We have heavy, wet snow and we have saturated ground and trees already weakened by last week's storm. Now we have this storm and we have the chance of additional damage. All our line crews and tree crews are out there, and we have out-of-state crews still here."

Gross noted that tree crews cannot work in buckets when winds are in the 35 mph to 40 mph range, but he said "restoration work is continuing elsewhere in the system" while buckets are down.

"We have people working on underground issues and issues in substations," he said. "We've also invested millions of dollars in smart switches where we're able to redirect power to an affected area, automatically reducing the number of affected customers."

Lessor said the area will be "stuck with a lot of clouds and a few isolated snow showers and flurries" over the next few days.

He also has his eye on another storm that could hit the area between Monday afternoon and evening.

"The bulk of the storm is going to pass out to sea to our east," he said. "But there's definitely the possibility that we do see some more snow."

Day Staff Writers Benjamin Kail, Martha Shanahan and Claire Bessette and The Associated Press contributed to this report.