SONOMA, Calif. – A 6.0 magnitude earthquake with the epicenter about six miles south of Napa woke residents and visitors about 3:20 a.m. (local). The jarring quake lasted about 25 seconds, and multiple aftershocks have been recorded.

Events today at Sonoma Raceway associated with the GoPro Grand Prix of Sonoma will continue as schedule. No damage was reported at the racetrack – about 15 miles from American Canyon epicenter – or its main arteries, California Highways 37 and 121.

The 2.385-mile, 12-turn road course and buildings at the facility have been inspected, according to a track spokesman. Emergency responders, including Holmatro Safety Team members, are on-site at the facility. No fans or campers were injured during the quake or its aftershocks.

Competition today includes the championship-deciding Indy Lights Presented by Cooper Tires race and the 85-lap GoPro Grand Prix of Sonoma at 1:40 p.m. (Pacific). NBCSN will telecast the Verizon IndyCar Series race at 1 p.m. (Pacific). Also, the race is broadcast on IMS Radio Network affiliates, XM209, Sirius 213, IndyCar.com and the INDYCAR 14 app.

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"What a wake-up call, scariest thing of my life," Verizon IndyCar Series driver Helio Castroneves said on his Twitter account.

"Whole hotel was moving back and forth rapidly," Graham Rahal tweeted.

The Sonoma County Sheriff's Office reported power outages in the city of Sonoma and surrounding area but no significant damage.

Structural damage and fires have been reported in Napa. It's the largest quake in Northern California since the Loma Prieta temblor in 1989. It is the strongest non-Alaska earthquake in the U.S. this year, according to the U.S. Geological Survey. Residents felt moderate tremors from the quake as far north as Sacramento and as far south as Santa Cruz.

Here are some additional social media reactions from our Verizon IndyCar Series drivers ...