CHICAGO -- Two people are dead and six others are recovering after a carbon monoxide leak in a Chicago apartment building.
Chicago fire crews responded to the building on Sunday.
Seventy-seven-year-old Rasheeda Akhter and 18-year-old Zanib Ahmed were rushed to the hospital, where they later died.
A few hours later, another person fell ill.
Authorities say a 74-year-old woman and five children between the ages of 5 and 12 ultimately were taken to the hospital.
Authorities say the building was checked twice for high carbon monoxide levels and nothing was found.
According to the Medical Examiner, 77-year-old Rasheeda died of carbon monoxide poisoning, but as for 18-year-old Zanib, her cause of death has yet to be determined.
According to the Chicago Fire Department, each floor of the building did not have a carbon monoxide detector as required by law.
Officials say exposure to low levels of CO over a long period of time is just as deadly as high levels over a short period of time.