One of those incidents happened at a PG&E substation in San Jose.
The Santa Clara County Sheriff's Department is now conducting a criminal investigation.
"PG&E notified us that they had a breach in their security fence and that somebody had actually gained access to the substation and damaged, I believe, they're either transformers or radiators," said Kurtis Stenderup of the Santa Clara County Sheriff's Department.
At least five of the seven banks of transformers appear to have been shot, causing them to leak oil.
Authorities in charge of the state's power grid are asking South Bay customers to conserve electricity at least until midnight Wednesday morning. So far, PG&E says there have been no outages and the state's Flex Alert warning is just a precaution.
"As we conduct the investigation there may be equipment that may need to be taken offline or out of service," said Nicole Liebelt of PG&E.
Just a short distance from the substation someone cut an AT&T phone cable leaving people in the city of Gilroy unable to call emergency services like 911 from their landlines.
"Being that they can't access it on landline right now, we've put out information on our TV station, our website, our Facebook page and so forth; allowing them or instructing them to use their cell phones," said Joe Kline from the City of Gilroy.
Businesses in Gilroy also suffered from the outages.
"We have no phones today, no phones, no computers. There's no online anything so it's been very quiet," said Kimberlee Dorris Rossi of Leedo Art.
Because the two incidents involving two key utilities happened so close together, authorities believe they are connected.
"All of this occurred within a half mile radius so because of the time frame and because of the geographical distance that these things happened, we believe that it's related," said Santa Clara County Sheriff Laurie Smith.
AT&T has offered up a $250,000 reward for information leading to the arrest and conviction of the people responsible for vandalizing their network.
Tips can be given to AT&T at 800-807-4205.
