The one-year-old bears died but their mother was not hurt in the Friday collision with the Canadian Pacific Rail freight, about 10 kilometres west of the Banff townsite.
Steve Michel, a wildlife specialist with the park, says the rail company informed the park about the collision on Friday night.
Michel says officials knew a female grizzly with two yearlings had been in the area before the accident.
A five-year research project with CP Rail to prevent collisions involving trains and bears was launched last year.
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