VIDEO: Here's where concrete chunks on Richmond-San Rafael Bridge came from, fell

SAN RAFAEL,Calif. (KGO) -- It's been an afternoon of headaches and confusion for drivers trying to cross the Richmond-San Rafael Bridge. Falling chunks of concrete forced the closure of one of the Bay Area's major thoroughfares late Thursday morning.

Engineers are trying to determine why the concrete chunks fell.

The CHP is warning of extremely heavy traffic and is urging drivers consider alternatives like the Bay Bridge or Highway 37.

Watch the video above for a look at where the concrete chunks came from and where they fell.

Take a look at full coverage on the Richmond-San Rafael Bridge closure due to falling concrete.