Durstige Menschen, die seit Stunden in der Hitze ausharren, sehen Wasser in den Wagen und rennen ihnen hinterher.
In this sentence from DW, why is there an "ihnen" behind "rennen"? It appears to me it should not be there.
The phrase "jemandem oder etwas (Dativ) hinterherrennen" means "to run after someone or something". In your example, "ihnen" refers to "die Wagen" (plural form of "der Wagen"). The pronoun "ihnen" is third person plural, dative.