NEW : Coast Guard initial assessment : Human error probably involved . It was crew 's first voyage on Thad Allen , which hit Bay Bridge in dense fog . Crew not allowed to leave ship due to federal law , says the National Oceanic and Atmospheric Administration . Some lawmakers , including one of the state 's U.S. senators , Democrat Barbara Boxer , have criticized the Coast Guard 's handling of the collision and resulting spill . Feds launch criminal probe ; only 140 gallons leaked and killed more than 250,000 birds .
NEW : Coast Guard initial assessment : Human error probably involved . It was crew 's first voyage on Thad Allen , which hit Bay Bridge in dense fog . Crew not allowed to leave ship due to federal law , says the National Oceanic and Atmospheric Administration . Feds launch criminal probe ; only 140 gallons leaked and killed more than 250,000 birds .