UPDATED 1/16/2014 1:10 p.m.

OAK BROOK (CBS) — A carbon monoxide leak Thursday morning in west suburban Oak Brook left an 84-year-old man dead and sent seven women to the hospital.

Authorities were called to a home on Oak Brook Hills Road around 9:45 a.m. for reports of people having trouble breathing.

Investigators are looking at an indoor pool heater in the 15,000-square-foot home as the possible cause for the leak.

An acceptable carbon monoxide reading is below 35 parts per million, but the home had a reading of 1,000 ppm.

“If they were in there for an extended period of time, it could have been fatal to all of them,” Gary Clark, Oakbrook acting fire chief, said of the victims.

The lone fatality – the 84-year-old man — was found dead in a bathroom. The seven women ranged in age from their twenties to their seventies; some of them were taken to Good Samaritans Hospital in Downers Grove.

Some of the occupants in the home were domestic help, authorities said.

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