LOS ALTOS — The cause of a weekend solo minivan crash that killed one person and left half a dozen with injuries was under investigation, authorities said.

Just after 4:55 p.m. Sunday, Santa Clara County Fire Department firefighters responded to reports of the crash in northbound Interstate 280 lanes at Magdalena Road just north of the Foothill Expressway on-ramp, fire officials said in a statement.

When firefighters arrived, they found a white Toyota Sienna that overturned, with seven people inside.Despite emergency life-saving measures provided by firefighters and paramedics, one person was pronounced dead at the scene.

Of the six injured, two people suffered major injuries, while two others sustained moderate injuries and the other two escaped with minor injuries. All were taken to an area hospital for treatment. Their conditions were not immediately available late Sunday.

California Highway Patrol officers also responded, calling a Sig-alert at 5:15 p.m. to alert drivers to seek alternate routes after three I-280 lanes were blocked. All lanes reopened around 8:20 p.m.

Anyone with information about the crash may call the CHP’s San Jose office at 408-467-5400.

Contact George Kelly at 408-859-5180.