It happened near East 75th and East 76th streets on 2nd Avenue.
A witness said one of the manhole covers flew 15 feet in the air.
The manhole fires caused elevated carbon monoxide levels in 240 East 76th Street to spike, and the building was temporarily evacuated as a result. There are stores on the first floor, including a Starbucks and a Pottery Barn Teen, and apartments above.
Levels quickly dropped, and people were allowed back inside.
Two people suffered minor injuries, but they were not taken to the hospital.
There were no reports of power outages.
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