Industrial sabotage by a rival of Verizon?
The only "rival" Verizon has is AT&T and AT&T needs those tiny pockets of Verizon country to "prove" that they are functioning in a competitive environment and not functioning as a monopoly that needs greater regulation. The same goes for Connecticut where the former SNET territory is now owned by AT&T and resides in the middle of Verizon country.
The fiber network is highly meshed. This sabotage was done by people who knew the physical topology of AT&T's fiber network and knew that they could isolate a geographical area by cutting the fiber at Blossom Hill and Monterrey in San Jose and on Old County Road in San Carlos. This is not obvious to someone who doesn't know what lives down man holes and what the CLLI codes of the hardware is.
It took out Verizon Services also. Verizon leases space on some of the cables.
Verizon technicians were on site working with AT&T technicians to get service restored.
It sounds like good old boys at the local had to many beers and went out doing some contract negotiations of their own.