It happened last April. It was a major incident, raising questions about who was behind it. There was little or no publicity about it across the nation.

It was an attack on an electric power station in California. Only now are we reading some accounts of it. Was it a terrorist act? The FBI said there is no evidence that terrorists were involved. It is still investigating.

This much is known, as stated by a former chairman of the Federal Energy Regulatory Commission, the attack was well-planned and executed by highly trained individuals.

The attack was at an electric transmission substation, located next to the Metcalf power plant near South San Jose. It occurred in the early morning hours. The attackers severed six AT&T fiber optic telecommunication lines in an underground vault, reportedly in a very professional manner. Then one or more persons began firing bullets, perhaps from assault weapons, and they blasted 17 transformers and six circuit breakers, and caused $15.4 million in damages. The firing reportedly went on for about 20 minutes.

No one was injured. No one lost power. But all agree it was carefully planned and carried out with precision, like a military operation. More than 100 fingerprint-free shell casings were found. A surveillance camera at Pacific Gas & Power Co.’s substation picked up a streak of light, maybe a signal from a flashlight, and then the snipers opened fire. The shooting stopped after another streak of light was reported. The shooters were gone by the time police arrived.

No group has claimed credit for the attack. While there was some publicity about the attack in California, the incident apparently didn’t draw much national attention by the media. It is being given considerably more publicity now. More and more people are just learning about it in recent months. At a congressional hearing in December, Rep. Henry Waxman, D-Los Angeles, said the incident makes it “clear that the electric grid is not adequately protected.” From reports, the attack is drawing more attention from government agencies now, and there is concern that the electric grid is not adequately protected from sabotage.

The need for added security is being emphasized. Was this an act of revenge against the power company? If it was, too many people likely were involved to give much weight to that theory.

A national syndicated columnist, Peggy Noonan, wrote that if the attack was replicated around the country, it could take out the entire electrical grid. Was this a practice drill for a larger attack? Is a big attack being planned? Cause for worry, yes! The company called it work of vandals. That may be the understatement of 2013. Noonan said our government always has to be pushed — in this case to sound an alarm there is a threat and prepare for it.

Maybe some officials are in a terrorist denial mode because they don’t want to alarm people. Still, the thought lingers: Was this a dress rehearsal for a larger attack?

No attack of this kind, in this magnitude, has ever happened before in this country.