Approximately 1.4 million homes and business are still without power in a storm-stricken area of the U.S. that stretches 1,100 kilometres from the Midwest to the Atlantic Ocean, days after a violent, deadly storm tore through the region.

Utility crews are racing to restore the electricity for a fourth sweltering day Tuesday, but they are warning it could be the weekend or later before the lights are back on in many neighbourhoods.

Transmission towers and electrical substations were among the damaged property Friday when the sudden, sustained storm system battered the region from Chicago to Washington with devastating straight-line winds.

Although it bore hurricane-like force, the "derecho" summer storm system materialized too quickly for any emergency preparations.

While emergencies were declared in Maryland, Ohio, Virginia, West Virginia and Washington, utility companies were left scrambling to organize the necessary equipment and get extra crews -- including hundreds of workers deployed from Ontario and Quebec -- needed to get power restored to the nearly 3 million homes and businesses that were left without power.

About 200 Hydro One employees from Ontario are helping restore electricity in Baltimore, Virginia, and Washington areas. Hydro Quebec has about 70 workers assisting local crews in Maryland.

"The toughest thing is getting around and seeing what feeds what ...this is an older grid here,” Hydro One employee Jake Davidson told CTV News as he examined downed wires in an Arlington, Va., neighbourhood.

The Hydro One crew working in the area will help restore power to about 300 people, supervisor Roger Fell said.

Among them is Nora Olave-Shibusawa, whose home had been in the dark since Friday. When she saw the Hydro One crew in her neighbourhood, she gave one of the workers a hug.

By focusing first on the substations that send power to thousands of homes and businesses, and then the distribution lines, crews have already restored electricity for more than 1 million customers. Because the transformers that can restore power to a few customers at a time are tackled last, residents of some pockets are being warned they may have to remain patient.

Baltimore Gas and Electric, for example, said in a letter posted on its website that its crews were working around the clock, but still expect their work to extend into the weekend.

"This type of widespread, extensive damage also complicates our ability to quickly provide accurate restoration times, especially when original damage assessments are revised upon closer inspection of the work required," the letter said.

A sense of urgency prevails, however, as the days since the storm have seen soaring temperatures that would put the lives of the sick and elderly at risk, even if there weren't widespread power outages.

"Above-normal temperatures will continue to affect a large portion of the country from the northern Plains to the Mid-Atlantic over the next few days," the U.S. National Weather Service said in a statement on its Facebook page, warning high temperatures could soar above 37 C Tuesday.

"Heat Advisories and Excessive Heat Warnings are in effect for many of the affected areas," inviting visitors to its website for details.

Officials have so far pegged the storms' death toll at 24. That number is expected to rise, however, due to the heat and the possibility of mishaps with the use of generators that emit fumes which can become deadly in enclosed spaces.

With a report from CTV’s Joy Malbon