Beautiful picture ! For information, it's not a TER, It's the TTGA (Touristic Train of Gorges de l'Allier). A lot a people take this train to visit de beautiful Gorges de l'Allier between Langeac and Langogne. Before, the SNCF organized this train with this composition but now the train belongs to "Train a vapeur d'Auvergne" association. Today, the SNCF is just in charge of hauled this train with a BB67400.
More information about the train and the touristic site : https://www.train-gorges-allier.com/?mobile=1
Be careful ! It's not the BB67556, It's the BB67557 !