Train to Pakistan
From IMDb: "Tensions run high near the border of British India, which is about to be partitioned with a new country called Pakistan. Sikhs living in this border town have heard numerous stories of Muslims killing, raping, and looting other Sikhs, Hindus, and Christians, and many of whom are their friends and relatives. Enraged at the loss of law and order, they plan their own attack on a trainful of Muslims leaving British India. The train is overcrowded with tens and thousands of migrating passengers, who are even perched on the windows and seated on the roof of this train. The plot is to tear the bridge down when the train is on it, and no one will dare stop these men to carry out this horrific task."