The CHP received reports a short time after 12:20 p.m. of a collision reportedly involving at least three cars on southbound Highway 280 at the Westborough Boulevard on-ramp.
One person involved in the crash has been confirmed dead, Officer James Evans said.
The southbound Highway 280 Westborough Boulevard on-ramp and one right-hand lane along the roadway have been closed and are not expected to reopen until around 3 p.m., the officer said.
The CHP issued a Sig-alert for the crash at 12:51 p.m.
