No power meant no air conditioning or fans as people coped with triple digit heat indices.
ComEd reports customer demand reached an all-time high peak usage , breaking the old mark set in August of 2006.
Many homes on the 7000 block of West Hiawatha were without power Thursday afternoon.
For Camille Schurer, this heat wave went from bad to worse.
"Tonight, we'll all have to go to my son's house because we can't stay here if we don't have power returned," she told ABC7.
Shurer said the lights went out at 11 a.m. It was the second time this week it has happened. ComEd said the outage was caused by a tree branch that fell on the line. Shurer said her block has had more than two dozen outages in recent years. She thought her recent equipment upgrade had helped until this week.
"You don't give me a band-aid anymore. That's not going to help," Shurer said.
The power was restored Thursday afternoon, but Shurer would like ComEd to investigate her chronic power problem.
"I would like equipment replaced, if that is what the problem is," she said.
There were also several residents in west suburban Oak Park without power, dealing with no air, no fans and no breeze. Harold Hohlen's Oak Park condo had no circulation. The air was hot, heavy and stifling as the heat index hovers around 110 for a second day.
"It is very difficult because we don't even have fans. No air moving, difficult to sleep. We don't have any hot water," said Hohlen, 72.
Hohlen and other residents in the complex were without power, they said, since Tuesday night because of an issue with the transformer and the meters. Hohlen said he thinks his appliances are now fried from a power surge.
ComEd said there is no overall issue with its system because of the heat. The company said these and other outages are isolated and could happen anytime.
"If there is no issue, I want them to come and visit me and the other people. I would like them to talk to people who lost their pets and tell me there is no issue when I'm sitting here with no electricity at all," Hohlen said.
A ComEd worker arrived at the building Thursday with a stack of new meters to replace the ones that are flashing "error."
Rick Smith was in the middle of moving into the building and can barely finish the job.The temperature read 87 in his apartment.
"You are sort of just pretty slow and lethargic," Smith said. "You can be a cranky or irritable person, and you have to meet people. It's interesting You have to rest a half hour and restore yourself before you can be a normal person."
Smith said he has been spending the night at friends' homes.
Residents of the comlpex told ABC7 their lights went back on Thursday afternoon, but the air conditioning and other appliances were not working.
The Chicago Fire Department was also busy Thursday responding to 911 calls from people overcome by the heat. Because of the number of calls coming in, the fire department added additional ambulance crews. Veteran fire officials said there was a similar spike in emergency calls during the deadly heat wave in 1995.
"In '95, if I can relate back to that, I remember it was about the fourth day or so when the runs went on a big swing. Hopefully, this will break within the next 48-72 hours," said Chief Robert Ambos, CFD.
Fire officials are warning city residents to not open fire hydrants. While the surge of water from the hydrants may be a tempting way to cool off, it causes a drop in water pressure and it's hampering firefighting efforts.
"They're not using proper equipment. We can't shut them down because of the damage," said Dist. Chief Tom Kennedy, CFD.
Health officials are reminding people that when it is this hot, the body even at rest can lose a quart of fluid an hour. Young children are especially vulnerable because their bodies take longer to adjust to the extreme heat.
"Staying cool, avoiding excessive exertion in this type of temperature environment and most importantly, to look after those around us, the elderly in our neighborhoods," said Dr. David Howes, emergency room physician.