A man and his teenage son would have died overnight had they not been removed from their home on Thursday in the Englewood neighborhood as it filled with deadly fumes.

Firefighters responded about 5:10 p.m. to the home in the 600 block of West Englewood for a report of a person having trouble breathing, according to Fire Media Affairs.

A 56-year-old man called 911 when his 16-year-old son complained of a headache and feeling lightheaded, the department said.

Firefighters found a gasoline generator running in the basement to power the home, which was without electrical service, the department said. Carbon Monoxide levels in the house measured over 1000 parts per million — a deadly level.

“Had they not been removed they would have perished overnight,” the department said on Twitter.

The man and his son were taken to University of Chicago Medical Center, where they were in good condition, the department said. The generator was shut off and the house was ventilated.