Con Ed says more than 30 manhole covers have been stolen from city streets and sidewalks in Brooklyn, Queens and the Bronx since early March.
The utility theorizes the thieves sell the covers for scrap metal. Witnesses have described people dressed in "utility apparel" but not Con Ed uniforms prying up the covers with car jacks.
Officials said the gaping holes are dangerous to New Yorkers.
"Anyone who steals these covers creates a serious hazard for pedestrians and motorists," Milovan Blair, Con Edison vice president for Brooklyn-Queens Electric Operations said in a statement.
The utility is urging anyone who sees suspicious activity around a manhole to call 911. Open manholes should be reported to Con Edison at 1-800-75CONED.
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