DANVILLE (CBS SF) – A big-rig carrying packages for the United States Postal Service overturned on Interstate 680 in Danville early Monday morning, killing the driver.

According to the California Highway Patrol, the crash was reported on Southbound 680 near the Diablo Road off-ramp at 3:24 a.m.

The CHP said the big-rig collided with a light colored van or SUV, causing the truck to overturn.

The big-rig driver was taken to the hospital, where he later died, the CHP said. Authorities have not released the driver’s identity.

Packages from the big-rig spilled onto the interstate. Most of the southbound lanes were closed for much of the morning commute, leading to major delays for Contra Costa County commuters.

As of 9:10 a.m. the right lane remains closed as postal officials pick up the packages. It is unclear when all lanes of southbound I-680 would reopen.