SAN JOSE (KPIX 5) — Thieves have broken into a Pacific Gas and Electric substation in San Jose which last year was the scene of a vandalism attack and shooting.

The Metcalf Road substation in south San Jose was broken into by someone cutting a hole in the fence and made off with construction equipment, according to PG&E.

In April 2013, someone cut fiber optic cables which knocking out some 911 service and fired a rifle at the same substation. The assailant or assailants appeared to have the objective of “shutting down the system,” according to Santa Clara County Sheriff Laurie Smith.

One former federal official characterized that attack as ‘domestic terrorism.’ The vandalism prompted legislation to beef up security at utility firms’ facilities.

PG&E said it has spent $100 million over three years to enhance the security of its substations.

In a prepared statement, PG&E said while the incident is still under investigation, a preliminary review suggested human error as the apparent cause of the security breach because fence detection alarms received in security operations ‘were not appropriately addressed.’

“First of all we take these matters very seriously and that’s exactly why we’re going to get to the bottom of exactly what happened,” PG&E spokesperson Joe Molica told KPIX 5.

PG&E also said there was no impact to the electrical grid, no equipment damage and no customers lost service. The utility asked for the public’s assistance for any information that could help lead an arrest of those involved in this latest incident.

Detectives spent the day collecting evidence and reviewing surveillance video.

“It’s a huge crime scene, as you can see this is a very big area. So obviously just the scope of it, the size of it is obviously challenging,” said Sergeant Kurtis Stenderup of the Santa Clara County Sheriff’s Office.

Anyone with information was asked to call the Santa Clara Sheriff’s Office 24-hour crime tip hotline at 408-808-4431.