Sniper Attack on Powergrid...practice run, or a sign of things to come?

I didn't see this any where on RP. The date was Feb 2014. NPR reports that a single sniper shelled 100 .50 cal rounds into 14 transformers from an unknown location. This seems to be a brilliant use of resources and demonstrates that we have weaknesses. Is this the future of terrorism? Was this an isolated event?
Can you imagine if this was done simultaneously in key locations throughout the US, how it might cripple our electrical grid? How can we prevent future attacks? What resources do we have that might be able to bring these vandals to justice?
Drones come to mind, National Guard OPs, cameras, and insider information...is it a worthy use of resources?

Here is an excerpt of the NPR article:
The top of the Journal's story grabs your attention:

"The attack began just before 1 a.m. on April 16 last year, when someone slipped into an underground vault not far from a busy freeway and cut telephone cables.
"Within half an hour, snipers opened fire on a nearby electrical substation. Shooting for 19 minutes, they surgically knocked out 17 giant transformers that funnel power to Silicon Valley. A minute before a police car arrived, the shooters disappeared into the night.
"To avoid a blackout, electric-grid officials rerouted power around the site and asked power plants in Silicon Valley to produce more electricity. But it took utility workers 27 days to make repairs and bring the substation back to life."
According to Foreign Policy, which was less definitive about whether the attack was the work of more than one person, at least 100 rounds were fired from at least one high-powered rifle.

No one has been arrested in connection with the attack.