In the Untouchables movie, how did Eliot Ness operate the liquor bust at the border?

In the film, the liquor raid at the Canadian border was done on horseback in sort of a "wild West" shootout fashion.

In real life, border raids did happen often, but not so often did they involve massive shootouts ... and a border raid on horseback would not be a standard mode of operation for Eliot Ness and his team.