About a dozen residents were treated on Saturday night after being exposed to carbon monoxide.
The exposure occurred at the Melia apartment complex in the 3400 block of Oakdale.
"Yea it was a scary feeling I mean we could have gone to bed and not woke up,” said tenant Michael Braun.
Braun was returning home with his wife after both were discharged from the hospital at about 3:30 p.m. Sunday.
"We had to go to the hyperbaric (chamber) for about two hours and then we had to spend the night continuing on the oxygen and then they just kept monitoring us,” said Braun.
Fire officials said they got the original call about 5 p.m. Saturday from hospital staff after a family of three checked themselves into the hospital with flu-like symptoms.
After examining the apartment building, crews evacuated 15 people from that complex and also had to force their way into two units to get to three of the residents who were already unconscious.
Fire officials believe the carbon monoxide was coming from the boiler room where the insulation around the boiler had caught fire.
After ventilating the building, crews let everyone return to their homes Saturday night. There were no carbon monoxide detectors at the complex.
"I want the complex to provide that. Think that they should provide that but if I go get one I'm going to bill them for it,” said Braun.
One of the three people found unconscious, a woman in her 20s, was expected to be released Sunday night, Braun said.