The FBI is investigating 11 attacks on high-speed Internet cables throughout the San Francisco Bay area. The perpetrator in each incident severed thickly protected Internet cables, though it's unclear if the attacks are being committed by the same person or group.

Internet cables, the glass wires that actually transmit broadband, are wrapped tightly in a thick bundle of fibers. The vandal broke into an underground vault and sliced completely through three lines Tuesday morning, the Federal Bureau of Investigation said, creating outages for Internet Service Providers Level 3 and Zayo near Sacramento. The first attack of this kind occurred on July 6, 2014, FBI Special Agent Greg Wuthrich told USA Today.

“When it affects multiple companies and cities, it does become disturbing,” he said. “We definitely need the public's assistance.”

Saboteurs destroyed fiber optic cables in four areas around California in 2009, and one incident in February left tens of thousands of Arizona residents, ATMs, police databases and other essentials without Internet access for a day.

Investigators haven't revealed much about the spate of 11 California cuts but observers said Tuesday's outage was “coordinated” and that they reflect a failure throughout the U.S. to protect valuable infrastructure.

"There are flags and signs indicating to somebody who wants to do damage: This is where it is folks," Richard Doherty, research director for the Envisioneering Group, a technology assessment firm, told USA Today. "You often have fiber from several companies sometimes going down the same street or the same trench. One attacker can dig one hole and wipe out service from three companies."