CHP arrested a Vallejo man on suspicion of driving under the influence of a drug Saturday in a "mass-casualty" crash near Napa’s Stag’s Leap Wine Cellars, which killed three people and sent four to the hospital with major injuries.

The accident happened Saturday around noon on Silverado Trail near Oak Knoll Avenue, about six miles north of Napa. CHP said the driver of a southbound Mitsubishi crashed head-on into a northbound Toyota sedan after side-swiping another vehicle, as NBC Bay Area reports.

Authorities are calling the crash a "mass casualty event," as victims had to be rushed to different hospitals for treatment.

One passenger in the Mitsubishi was pronounced dead at the scene, and another died at the hospital. Four people in the Toyota were hospitalized with major injuries, where one of them later died, authorities said.

The driver of the Mitsubishi, who was identified as William Brumley, 68, of Vallejo was taken to Santa Rosa Memorial hospital and is expected to survive, according to the Chronicle.

The crash was reportedly located near Stag’s Leap Wine Cellars, but it was unclear whether the driver had been to the winery prior to the crash.

The identities of the passengers who were killed have not been released, and the investigation is ongoing.

Silverado Trail was closed for several hours during the investigation and was reportedly reopened to traffic at 6 pm Saturday.

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