A 5.6-magnitude earthquake struck Mendocino County on Wednesday morning, triggering ShakeAlert notifications across Northern California.

The quake hit at 8:10 a.m. Pacific Time, centered about seven miles north of Redwood Valley, a lightly populated area in inland Mendocino County, according to the U.S. Geological Survey.

USGS also reported a preliminary 2.5-magnitude earthquake in the same area about seven minutes later, a possible aftershock, followed by likely aftershocks measuring 2.7 and 2.6 about an hour later.

Some injuries have been reported, according to the Mendocino County Executive Office. The extent of the injuries was unknown, but officials confirmed there have not been any deaths.

Shaking was felt as far away as Sacramento, and some power outages were reported in Willits near the earthquake's epicenter. PG&E's map showed the outage starting at the same time the earthquake struck, with the utility provider saying 8,000 customers were impacted.

PG&E added that there has not been any damage to its equipment, but it activated its emergency response plan for crews to respond to gas and electric hazards. The utility company will continue to patrol and assess for damage.

USGS placed the quake at a depth of about 5 miles. Its impact alert level was listed as yellow, meaning some damage is possible.

The National Tsunami Warning Center said there was no tsunami warning, advisory, watch or threat from the earthquake.

Fort Bragg police, about 50 miles west of the epicenter on California's North Coast, said they were monitoring the situation and that no damage had been reported there. Mendocino County added that it's not aware of any major damage, but crews were continuing to assess the area. 

California Gov. Gavin Newsom's office said he has been briefed on the earthquake.

Redwood Valley is located about 120 miles north of San Francisco, and about 140 miles northwest of Sacramento.