WASHINGTON — Utility crews struggled to catch up with a backlog of millions of people without electricity for a fourth hot day Tuesday as frustration grew and authorities feared the toll of 24 storm deaths could rise because of stifling conditions and generator fumes.
Power was back for more than a million customers but lights — and air-conditioning — were still out for about 1.26 million homes and businesses in seven states and the District of Columbia. The damage was done by powerful wind storms that swept from the Midwest to the Mid-Atlantic late Friday, toppling trees and branches into power lines and knocking out big transmission towers and electrical substations.
Utilities were warning that many neighborhoods could remain without power for much of the week, if not beyond. Public officials and residents were growing impatient.
‘‘This has happened time after time and year after year, and it seems as if they’re always unprepared,’’ said John Murphy, a chauffeur from Burtonsville, Md., who was waiting for Pepco to restore power Monday.
The wave of late Friday evening storms, called a derecho, moved quickly across the region with little warning. The straight-line winds were just as destructive as any hurricane — but when a tropical system strikes, officials usually have several days to get extra personnel in place.
So utility companies had to wait days for extra crews traveling from as far away as Quebec and Oklahoma. And workers found that the toppled trees and power lines often entangled broken equipment in debris that had to be removed before workers could get started.
Adding to the urgency of the repairs are the sick and elderly, who are especially vulnerable without air conditioning in the sweltering triple-digit heat. Many sought refuge in hotels or basements.
Officials fear the death toll, already at 24, may climb because of the heat and use of generators, which emit fumes that can be dangerous.
After Maryland reported Monday that three people had died in the recent heat wave — the deaths were not storm-related — Deputy Secretary Fran Phillips emphasized that people who are in areas without power need to take advantage of cooling centers.
At the Springvale Terrace nursing home and senior center in Silver Spring, Md., generators were brought in to provide electricity, and air-conditioning units were installed in common rooms to offer respite.
Residents using walkers struggled to navigate doors that were supposed to open automatically. Nurses had to throw out spoiled food, sometimes over theobjections of residents.
The lack of power upended many daily routines. Supermarkets struggled to keep groceries from going bad. People on perishable medication called pharmacies to see how long their medicine would keep. In Washington, officials set up collection sites for people to drop off rotting food. Others held weekend cookouts in an attempt to use their food while it lasted. And in West Virginia, National Guard troops handed out food and water and made door-to-door checks.
Last year, it took Baltimore Gas and Electric company 8½ days to restore service to all 750,000 customers who lost power during Hurricane Irene.
Baltimore Gas and Electric said on its website that it would take hundreds of thousands of man-hours to clear debris and work through outages.