A seven-year-old boy died and his grandmother was seriously injured in an apartment fire in New York City as the FDNY deals with staff shortages in response to a vaccine mandate. 

Firefighters responded to a 1:30 a.m. call Saturday at a building in Washington Heights, where fire broke out in the building superintendent’s basement apartment. First responders quickly contained and extinguished the fire. 

Five people were inside the apartment at the time, including Robert Resto, 7, the super’s grandson, and the super’s wife, 54. 

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Resto was pronounced dead inside the apartment, ABC 7 reported. The super’s wife was taken to Jacobi Hospital and listed in serious condition. 

Resto was found hidden under a bed severely burned.

The fire ignited as firefighters across the city called in sick Friday, but the FDNY said it hadn’t closed any firehouses due to staffing shortages. 

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City Fire Commissioner Daniel Nigro said it was "unacceptable" for "a group of our firefighters" to demonstrate their anger at the citywide vaccine mandate in a way that "may endanger the lives of New Yorkers." 

"Despite these actions by some, the department will continue to respond to all calls for help that come our way," Nigro promised. 

FDNY officials insist the "sickout" did not affect response times to Saturday's fire, the New York Daily News reported. Firefighters arrived within four minutes. 

FDNY UNION LEADER WARNS COVID VACCINE MANDATES WILL SPIKE EMERGENCY RESPONSE TIMES, SEND CITY INTO ‘CHAOS’ 

By Monday, any FDNY employee who has not received at least one shot of a COVID-19 vaccine will be sent home without pay. 

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Around 72% of the city's firefighters and 84% of medical first responders had at least one dose of the vaccine as of Friday night.