One motorcyclist died and two others were seriously injured after separate crashes in Napa and Sonoma counties Sunday afternoon.

The fatal crash occurred around 1:40 p.m. when a man riding his motorcycle east on Highway 128 east of Lake Hennessey in Napa County lost control and struck a fire truck traveling in the opposite direction.

Life-saving efforts were attempted on the scene but the motorcyclist died, according to CHP dispatch records.

In Sonoma County, a couple on a motorcycle both suffered major injuries around 3:15 p.m. when they crashed into a Mercedes-Benz on Calistoga Road near Porter Creek Road, according to the CHP.

The man and the woman, neither of whom was wearing helmets, were taken — one by helicopter — to Santa Rosa Memorial Hospital.

Their conditions were not available by press time.

You can reach Staff Writer Kevin McCallum at 707-521-5207 or kevin.mccallum@pressdemocrat.com. On Twitter @srcitybeat.