There have been reports of the smell coming from Santa Rosa, Concord and Vallejo. The problem began in the northwest where a natural gas supplier mixed in too much mercaptan.
Wednesday evening in Vallejo Kiana Slavaugh may have gotten a whif.
"I was going to ask my neighbors if they left the gas on or something, but I really didn't do anything about it," said Slavaugh.
"And it went away?" asked ABC7's Terry McSweeney.
"Yeah, well I'm hoping it went away. I went to bed," said Slavaugh.
A number of the folks who smelled it did not got to bed or continue sleeping --18 called the Vallejo Fire Department on an already very busy night.
"We had a two-alarm fire in one area of town and a three-alarm fire in another area of town and then we had another fire on another side of town. But the biggest problem we had, other then fires, were the gas leaks," said Vallejo Fire spokesman Bill Tweedy.
The overdose of odorizer is moving south, the Central Valley may be hit hard, but large parts of the Bay Area may be spared.
"Once the gas gets into the Bay Area, there are a number of other transmission sources that also feed into Bay Area, we expect it to dilute pretty quickly," said David Eisenhower of PG&E.
For those who smell gas and hesitate to call 911 because it might turn out to be a false alarm, fire fighters say make that call.
"We would like you to call 911 and PG&E and inquire about it and see if we can come out and take a look. There are some things that you can do on your own, such as make sure that all your pilot lights are lit and no gas lines are open that aren't burning," said Contra Costa Fire District Batt. Chief Kevin Nieland.
PG&E is telling customers if they think there is a gas leak to still call 1-800-743-5000 to report it