SAN DIEGO (CBS) — A widespread power outage that hit Southern California last week may have cost the region an estimated $118 million.

KNX 1070′s Tom Reopelle reports the area powered by San Diego Gas & Electric lost what one researcher estimated could be as much as $10 million per outage hour.

“First, we looked at the amount of food that was likely lost,” said Eric Bruebold with the National University System Institute For Policy Research. “The second main impact was overtime for public safety officers.”

The study also considered the loss of productivity suffered during the outage that affected the region from the California – Mexico border all the way as far north as southern Orange County.

Many businesses had to close their doors as much as four hours earlier than normal, Bruebold said.

The total losses do not include outlying areas like Imperial County and Arizona, and data for how much the Mexican economy lost may never be determined.

Federal investigators are still looking into what may have caused the outage.