It happened before 2 a.m. Wednesday at 38th Street near Second Avenue.
Residents shared video of smoke billowing up through the street.
No injuries were reported.
The blast knocked out power to some homes and businesses in the area.
Manhole explosions cut power
Police shut down Second Avenue in the area for nearly three hours as repair work got underway.
The road was back open by 5 a.m.
Access to the Midtown Tunnel was not affected.
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