Lawmakers are pushing to impose federal standards for protecting the country's electric grid from attack in the wake of a new report about a sniper assault on a California electrical substation last year that has raised fears the power grid is vulnerable to terrorism.

The Wall Street Journal reported Thursday that Sen. Dianne Feinstein, D-Calif., said she and fellow senators plan to ask the Federal Energy Regulatory Commission, which has jurisdiction over the electric grid's reliability, to "set minimum security standards for critical substations."

The April 16, 2013 the attack on Pacific Gas & Electric’s Metcalf transmission substation involved snipping AT&T fiber-optic lines to knock out phone and 911 service, and firing shots into a PG&E substation, causing outages. The assault had not been widely publicized until The Wall Street Journal reported new details in a story on Wednesday.

The FBI is the lead agency in the investigation and an agency spokesman told the newspaper it doesn’t think the incident was a terror attack. However, Jon Wellinghoff, chairman of the Federal Energy Regulatory Commission at the time, called it "the most significant incident of domestic terrorism involving the U.S. power grid that has ever occurred."

The incident began when intruders lifted heavy manhole covers at about 1:30 a.m. in two places on Monterey Highway south of San Jose, climbed under the road, and cut AT&T fiber optic cables, temporarily knocking out 911 service and phone service.

In a 19-minute period, gunmen fired more than 100 rounds into substation equipment, disabling 17 of 20 big transformers, causing about $16 million in damage, according to The Wall Street Journal. No arrests have been made in the case.

In December, during an oversight hearing, Rep. Henry Waxman, D-Calif., described "an unprecedented and sophisticated attack on an electric grid substation with military-style weapons. Communications were disrupted. The attack inflicted substantial damage."

He said he would withhold details of the incident to avoid harming the investigation but added he had been in touch with the FBI about it.

One proposal being discussed in Congress is would give the Federal Energy Regulatory Commission the power to write and impose interim rules on grid defenses. The utility industry would still be able to influence any permanent requirements, according to the Journal.

Rep. Trent Franks, R-Ariz., said "the last thing I want to do is regulate any industry." But he told the newspaper utilities must do more to protect the grid for the sake of national security.

Under current law, the commission has to accept or reject proposals written by an industry-dominated group, but cannot alter them, according to the report.

Some utility industry executives told the Journal it would be difficult to come up with rules for improving security that would work in both urban and rural areas.

"One size fits all may not get you true resiliency," said Lisa Barton, executive vice president of transmission for American Electric Power, adding that increasing protections could be costly. "I'm not saying it isn't worth it," she said.

The Associated Press contributed to this report.

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