A heat wave pushed East Coast temperatures into the 90s for a third day Tuesday, leading utilities to impose power conservation that blacked out tens of thousands of homes and sent some children home early from hot classrooms.

``But at least you don't have to shovel the heat,'' said Charlene Adair, wheeling her twins in a stroller down Main Street in Springfield, Mass.

A week ago, her twins were still in snow suits, when a cold snap dusted the Appalachians with snow and nipped young vegetables in the bud.

The unexpected heat wave, which occurred so early in the year that some utilities had generators out of service for maintenance, blacked out power to more than 100,000 people in New York City, where the temperature reached a record high for a second day in a row.

Tuesday afternoon temperatures reached record highs of 96 at Newark, N.J.; 93 in New York City and 95 at Wilmington, Del. Farther south, Greenville and Spartanburg, S.C., registered a record 91.

A line of thunderstorms marched through the region by evening, snapping the heat wave. Most areas saw the mercury drop into the 70s.

As people cranked up air conditioners and fans earlier in the day, power supplies were quickly stretched dangerously thin across the Northeast.

The New York Power Pool told utilities around the state to conserve power, and Con Edison reduced available voltage in the New York City area by 8 percent. That cut off power to more than 100,000 people in the borough of Queens.

``We finally cut power to about 115,000 people,'' said Con Ed spokesman Earl Wells.

The power was cut at about 5:45 p.m. because of faults in two transformers at a substation and a severe overload of the system. It affected a wide section of the borough of Queens, and was not completely restored until nearly midnight.

``It was directly related to the heat,'' said another Con Ed spokesman, Richard Mulieri. ``Usage was just too high and there was no way around it.''

Extra police officers, firefighters and paramedics were sent to patrol the affected neighborhoods until power was restored.

In Connecticut, two 10-year-olds were injured when a transformer exploded near their school bus. The explosion was storm-related, but police weren't sure it was because of lightning or downed wires. High winds that felled trees and power lines shut off power to more than 70,000 people in Connecticut.

In Maryland, Delaware, Pennsylvania and New Jersey, a consortium of utilities reduced power by 5 percent.

``It's all weather-related and there are some major units off line (for maintenance or repairs),'' said Rick Hofmann, spokesman for Delmarva Power & Light Co. of Wilmington, Del.

And some people didn't have working air conditioners to turn on.

``We took over 250 calls yesterday and we're working on that (number) today,'' said Madelene Sweeny, a dispatcher for Garden State Air Conditioning in Freehold, N.J. ``We're two weeks behind if you're looking for service.''

Schools sent children home early to get them out of classrooms that lacked air conditioning.

At White Sulphur Springs Elementary in White Sulphur Springs, W.Va., the principal's office was one of the few rooms with air-conditioning.

``But we do not turn that on until after 3 o'clock,'' said secretary Debbie Fogus. ``We don't think it's fair to everyone else.''

The heat prompted the Capital Area Agency on Aging in Richmond, Va., to get an early start on its summer program providing fans to low-income seniors.

Even ice makers looked for relief as they tried to keep up with demand.

``I probably change shirts three or four times a day,'' said Fred Schuld, owner of the Ice Factory in Landing, N.J. ``Once in awhile you walk into the freezer and get a blast of cool air. That's about it. You sweat from morning to night.''