It was shortly after midnight when 39-year-old Richard Fox allegedly set off his homemade cannon in the remote mountain community of Potrero, authorities said.
The cannonball smashed into their mobile home, killing the 38-year-old woman. Four others inside the home, including the couple's 4-year-old daughter, were not injured.
Fox was treated at a hospital for shrapnel wounds to his right leg and arrested for investigation of exploding a device resulting in death. Investigators believe he was under the influence of alcohol at the time of the incident.