Updated 04/18/13 – 10 p.m.

CHICAGO (STMW) — Thursday’s spring storm, which brought lightning strikes, high winds, heavy rain and flooding, knocked out power to thousands of ComEd customers throughout the Chicago metropolitan area.

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At the height of the storm, more than 21,000 ComEd customers were without power, according to a utility spokesperson.

By Thursday night, ComEd was reporting 4,700 outages system-wide. Most of those were in the North Region, where 2,000 customers were without power.

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In the city of Chicago, 200 customers were without power, while there were 2,200 outages in the South Region, and 300 in the West Region.

ComEd stressed the importance of exercising caution in the wake of the storms, especially around downed wires and standing pools of water.

“We really want everybody to stay safe,” ComEd spokeswoman Kim Morris-Johnson said.

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Around downed power lines, people may not be sure if those lines are live, but, “assume they are, and give (ComEd) a call,” Morris-Johnson said. “We want everyone to be extremely careful and extremely cautious.”