The 86-year-old man, Pei Tang Yeh, was found unresponsive in a bathroom of the home. There were eight other people in the home, ages 20 to 70, some family and some domestic help.
The Oak Brook Fire Department was called to a home in the 2900-block of Oak Brook Hills Road about 9:45 a.m. for a female having difficulty breathing. Firefighters found high levels of carbon monoxide upon arrival, and measured 1,000 parts per million, said Acting Fire Chief Gary Clark, who said symptoms of carbon monoxide poisoning begin to appear at 200 parts per million.
"This home has several furnaces, we saw a boiler... a couple of hot water heaters," said Clark.
Firefighters said they did not hear CO alarms. The gas was shut off, the home evacuated -- but not before some confusion due to a language barrier.
"The only thing we can say at this point is the fire department had determined there were higher levels of carbon monoxide in that general vicinity," said Chief James Kruger, Oak Brook Police Department
Police do not believe foul play was involved. Clark said the carbon monoxide readings were strongest near an indoor pool of the approximately 15,000-square-foot house, and that is being investigated as a possible source. There is a heating system for the swimming pool.
Ambulances from five departments responded to the home and helped transport victims to Good Samaritan Hospital in Downers Grove.
The Sun-Times Media Wire contributed to this report.