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 .
NEW : Coast Guard initial assessment : Human error probably involved . It was crew 's first voyage on Cosco Busan , which hit Bay Bridge in dense fog . Crew not allowed to leave ship due to federal law , says Coast Guard . Feds launch criminal probe ; 58,000 gallons leaked and killed nearly 400 birds .