Blossom Star Mayim Bialik Seriously Injured In Car Accident

It all went down on the corner of Hollywood Blvd. and La Brea around noon ... sources tell us the former "Blossom" actress was traveling alone in a white Volvo which was struck in the intersection by another vehicle filled with tourists from Chile.

We're told emergency responders raced to the scene. One source tells us there was "tons and tons of blood everywhere."

Sources tell us Bialik sustained major damage to her hand ... and "her finger was almost completely severed ... it was just hanging there."