Thunderstorms swept through the Chicago area Monday morning, pelting commuters and leaving more than 765,000 Commonwealth Edison customers without power at the storm’s peak, and more than half a million still without power Monday afternoon. Storm was ‘largest ever’ for ComEd with 765,000 losing power SUN-TIMES MEDIA WIRE July 11, 2011 7:28AM Reprints 15Share ARTICLE EXTRAS View Gallery RELATED STORIES Person shocked by downed wire in Pilsen 6 hurt when large tent blows down at southwest suburban college Updated: July 11, 2011 3:52PM Severe thunderstorms swept through the Chicago area Monday morning, pelting commuters and leaving more than 765,000 Commonwealth Edison customers without power at the storm’s peak, and more than half a million still without power Monday afternoon. It was the “largest storm we’ve ever experienced in terms of the number of customers affected,” ComEd’s senior vice president of customer operations Fidel Marquez said, comparing the weather to “a blitzkrieg.” Power outages from the storm are still affecting ComEd customers Monday afternoon. Though 480 crews are out working to restore power, and additional workers have been called in from Iowa, Missouri, Wisconsin and Pennsylvania, it could take several days before all customers have power, Marquez said. As of 1 p.m., 178,000 customers had seen their power restored. The hardest hit region was in the northern suburbs, where 254,000 are without power. In the west suburbs, 126,000 are without power and in Chicago and Maywood, 103,000 customers were affected, the spokesman said. In the south suburbs, 80,000 customers are without power Monday afternoon At the height of the storm, more than 765,000 customers were affected, Marquez said. The number of customers who lost power tops the previous high of 684,000 recorded during a storm in August 2007. One Chicago Streets and Sanitation department worker was injured. The worker, 60, was on the phone inside the city offices at 2352 S. Halsted when a post holding a power line outside was damaged, giving her a bad electric shock, colleagues said. She was taken to the University of Illinois at Chicago Hospital in serious to critical condition at 9:20 a.m., according to the Fire Department, but was doing OK later Monday, colleagues said. A Cook County sheriff’s deputy and two convicts the deputy was supervising in south suburban Palos Hills were also being treated for injuries Monday afternoon after a tent collapsed during the storm. The deputy was hit in the head by a tent pole, but is expected to be released from hospital later Monday. The convicts, who were helping clear up the suburb’s Family Fest event through the Sheriff’s Work Alternative Program, were also expected to be released from the hospital Monday. The heavy rain, hail and winds downed power lines throughout the city and sent trees into streets. In the aftermath of the storms, the National Weather Service issued a Lakeshore Flood Warning for the shore of Lake Michigan. A strong line of storms that moved across the lake caused water to build up along the Michigan and Indiana shores. The water will flow back toward the Illinois shoreline. This phenomena is known as a seiche, the weather service said. Within this warning, water levels rose and fell, in some cases by two or more feet. The warning along Illinois shores expired at 1 p.m., and water is now rushing back east, with a flood warning in effect for LaPorte County, Ind., and Berrien County, Mich., until 7 p.m. Lifeguards at North Avenue Beach in Chicago saw the effects of the seiche and warned swimmers to stay in knee-deep or shallower water. Meanwhile, lake levels at Calumet Harbor fluctuated by almost two feet, the weather service said. Meanwhile, flights in and out of O’Hare International Airport were delayed 45 minutes, and more than 100 flights have been canceled, the city Aviation Department reported. At Midway Airport, some airlines are experiencing delays averaging 50 minutes, with one cancellation reported, officials said. Trains were either halted or delayed during the heavy storms, according to both the CTA and Metra. On Metra, due to weather-related high winds, Union Pacific North Line, Northwest Line and West Line trains were stopped, according to Metra spokesman Michael Gillis. On the BNSF Railway line, trains were traveling at a reduced speed due to the winds, Gillis said. All other lines were operating normally. The CTA was honoring Metra tickets on Union Pacific trains during the morning delays. Meanwhile, the CTA encountered its own delays due to the severe weather. The agency said all trains were experiencing “major delays” during the storm. Downed trees on tracks on the Purple, Red and Yellow lines temporarily halted service. Yellow Line service was restored by about 9:40 a.m., while Red Line service was restored at 9:50 a.m., CTA spokeswoman Wanda Taylor said. The Purple Line is running on a single track northbound between Linden and Howard because tree debris remains on the southbound tracks, Taylor said. At the height of the storms, the National Weather Service Doppler Radar indicated a line of storms were capable of producing winds in excess of 60 mph.