The scene of a shooting and oil spill at a San Jose PG&E substation on April 16, 2013. (CBS)

SAN JOSE (CBS SF) – In apparent acts of “sabotage” in the South Bay early Tuesday, someone cut fiber optic cables, knocking out some 911 service, and then fired a rifle at a PG&E substation, Santa Clara County’s sheriff said.

The vandal’s objective appears to have been “shutting down the system,” Sheriff Laurie Smith said at a news conference at the substation Tuesday afternoon.

“We don’t have a suspect,” she said. “It seems like the same perpetrator or perpetrators to me.”

Both incidents happened early Tuesday morning in the area of Metcalf Road and Monterey Highway, just southeast of San Jose city limits.

The underground cables, protected by manhole covers, were cut shortly before 1:30 a.m. in two locations along Monterey Highway, Smith said.

Some of the cables, comprised of bundled fiber optic cords, were cut near Monterey Highway and Coyote Ranch Road, AT&T spokesman George Ross said.

He said the cables there are AT&T lines but that some other service providers piggyback off of them.

A number of South Bay customers lost landline and cellphone service, and the damage also initially knocked out some 911 call systems in the area.