Chicago, IL — An elderly woman is dead and an elderly man is in critical condition after an apparent carbon monoxide leak in an apartment on Chicago’s Northwest Side.

Police say officers were called to the apartment shortly after 1 a.m. Wednesday.

Officers found 75-year-old Sandra Perez and an 80-year-old man whose name has not been released unconscious on the bedroom floor of the apartment.

Both were taken to a nearby hospital where Perez was pronounced dead.

No foul play is suspected and police say there were high levels of carbon monoxide inside the apartment.