A chain-reaction crash involving seven vehicles clogged a Napa County highway Monday night but caused no major injuries, the CHP said Tuesday.

The 7:50 p.m. crash resulted in three people going to Queen of the Valley Hospital and major damage to four vehicles.

It also involved three new cars and drivers from Napa, Solano, Lake counties and one from Canada, according to a CHP report.

It started at 7:50 p.m. with driver Nicholas Masters, 66, of Lower Lake.

Masters was driving north on Highway 29 through Rutherford when his 1998 Dodge Ram crossed the double yellow lines, CHP spokeswoman Officer Anna Paulson said.

The truck ran over a two-foot asphalt center median strip and into the southbound path of a 2010 Chevrolet Equinox driven by Janet Myers, 49, of Napa.

Masters' pickup hit the left side of Myer's Chevrolet and then got in the way of a 1990 Toyota Cressida driven by Steven Nagle, 59, of Suisun City.

The truck crushed the front of Nagle's sedan, before hitting the side of a 2013 Mercedes E-350 driven by Douglas Perks, 67, of North Vancouver, British Columbia.

Masters then hit the back of a 2013 GMC Terrain driven by Megan Balaguy, 32, of Napa.

The next car struck, driven by Maria Vargas, 36, of Napa, was a 2013 Dodge Dart, causing major damage to the Dart.

The final crash was with a 2006 Dodge Ram pickup, causing major damage to the Dodge driven by Jose Rangel Lara, 39, of Vallejo.

Masters' truck also had major damage.

What caused Masters to lose control remained under investigation Tuesday. Alcohol or drugs didn't appear to be involved, Paulson said.

Drivers Masters, Nagle and Vargas went to the Napa hospital with suspected minor injuries.