The incident happened just before 8 p.m. inside 838 Hunts Point Avenue.
An 81-year-old woman is in critical condition due to carbon monoxide poisoning.
A man was also injured and is listed in stable condition.
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Both victims were transported to Jacobi Hospital.
FDNY officials say elevated carbon monoxide levels were detected.
FDNY members vented and secured the scene.
An investigation is underway to determine the cause of the leak.
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