Fresno, CA – Two people died in a Central California home from lethal levels of carbon monoxide in the house.

The Fresno Bee reports that crews on Wednesday found levels that were at least 10 times higher than they would have reached had there been a working carbon monoxide detector in the home.

Authorities have not released the names of the man and the woman who were found dead in the Fresno home.

A man working on the home discovered the victims and called police. When officers arrived they smelled the gas and called the fire department to help.

Fresno Firefighter Pete Martinez says a CO detector, which is required under California law, could have alerted the residents to the amount of lethal gas in the home.