Six people have been hospitalized in San Antonio, Texas, due to carbon monoxide poisoning.
San Antonio Fire Department Battalion Chief Jonathan Jones told the San Antonio Express-News that three people were transported to the hospital, one with life-threatening injuries, on Saturday evening.
Three others had admitted themselves complaining of flu-like symptoms. When doctors determined it was carbon monoxide they alerted the fire department.
Jones said the gas had been released by burning insulation on a water heater in the building. In total, 16 units were evacuated.
Carbon monoxide is odorless and colorless and can lead to death by suffocation.