As the snow left by Winter Storm Jonas melts, 400 manhole fires have broken out in New York in the past week.

Sparks can be caused by snow runoff mixing with salt, NBC reported, stating that such occurrences can lead to manhole explosions as well as power outages, which have been reported in all five boroughs this week.

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"This is happening with the snow runoff and the salt getting into the underground electrical structures," Con Ed spokesman Mike Clendenin said to NBC. "Water and salt is not a good mix." 

Con Ed told NBC that 400 manhole fires have occurred since the most recent blizzard, with 60 fires on Wednesday alone.

Residents have been injured in past winters by flying manhole covers, and carbon monoxide from manhole-fire smoke can leak into area homes, Gothamist stated in a related report.

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According to Con Ed, people should stay away from smoking manholes and contact the FDNY or Con Ed right away, NBC added.