FBI officials sent out a memo warning of terrorist attacks at Super Bowl 50 that could take out the entire fiber-optics system that feeds the arena.
"If the fiber-optic cables get cut, it impacts financial institutions, impacts Silicon Valley," said retired assistant Special Agent in Charge Jeffrey Harp, to KPIX 5. "It impacts a lot of infrastructure in that area."
The FBI said it hadn't received a specific threat about the Super Bowl. But agents also said they've identified several danger zones outside the stadium they're going to protect as well, CBS News reported.
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"It's the lone wolf," Harp said. "It's the individual who is self-radicalized that creates a problem that you can't detect. There's only so much the FBI can do with regard to surveillance within the guidelines of the Constitution."
Harp mentioned specifically the risks of drones.
"If someone were to use a drone to disperse something," he said, CBS News reported, "it could be a potentially hazardous situation."