A major crash involving a big rig, which sparked a massive fireball, shut down all southbound lanes at the Interstate 80 split in San Francisco. According to reports, "The CHP has issued a Sigalert and is urging motorists to use alternate routes."

Other cars were also involved in the crash. No word yet on how many injuries.

Update: According to KRON 4 Morning News, the crash occurred in front of a UPS building at "Hospital Curve." At least 6 other vehicles were involved in the crash. If you need to get to San Francisco, do not use 101.

Octavia and upper deck of Bay bridge are all affected, with the latter dumping traffic off on Fremont and Ninth Street. Do not use the Bay Bridge to get into SF.

Update II: Highway 101 in SF will remain closed at least until noon.

Update III: All lanes on Highway 101 have reopened.