ANTIOCH, Ill. (CBS) — An Antioch family is lucky to be alive after they were overcome with deadly carbon monoxide fumes early Monday morning.

CBS 2’s Mike Parker reports.

Paramedics and fire crews worked frantically to bring out a husband, his wife and their two daughters from their home.

First-responders found them unconscious and near death. One of the daughters had called her boyfriend and said the entire family was sick with headaches and nausea.  The young man raced to the house and through a window saw the girl’s father passed out on the living room floor and called 911.

The dispatcher asked, “Is he breathing and conscious?”

“It looks like he’s unconscious. I can’t tell,” the boyfriend said.

It was carbon monoxide, apparently from a heating system malfunction, according to fire officials.

Responders got a reading of 600 parts per million in the home, according to Antioch Fire Chief John Nixon. One hundred parts per million can be fatal, he said.

The oldest daughter and her parents were treated and released from hospitals. The youngest daughter, who is 12, was still receiving treatment.

The fire chief says he wants to shake the hand of the young man who made that 911 call.

“Had he not called 911 and been at the premises, that family would have passed away,” Nixon says.

Reached by CBS 2, the good Samaritan said he preferred not to talk about what happened.

The fire chief said there were no working carbon monoxide alarms in the house.