San Francisco Bay area residents are preparing for a second wave of power shut-offs as part of a precautionary measure to prevent additional wildfires in the region. Pacific Gas and Electric, PG&E, was preparing to begin shutting off power to customers in Alameda, Contra Costa, Santa Clara, and San Mateo counties late Wednesday. Santa Clara County officials declared a state of emergency ahead of the power outage. Dave Flamm, deputy director of Santa Clara county’s Office of Emergency Management, told the San Francisco Chronicle that the county could potentially have over 100,000 individuals without power for a number of days, without knowing the exact duration of the event. “We want to ensure that we’re properly postured and placing the right gravity on this event,” Flamm said. PG&E officials said a “severe wind event” expected across Northern California prompted the drastic move, with an estimated 750,000 customers losing power. The outages could last up to a week for some customers, affect more than 2 million people and, according to some estimates, cost businesses and residents more than $1 billion, the Chronicle reports.