KM3NeT is a next-generation research infrastructure housing large volume neutrino telescopes in the Mediterranean sea. KM3NeT comprises two detectors, KM3NeT/ARCA and KM3NeT/ORCA, which will consist, once fully deployed, of 198 and 108 vertically-arranged detection units, respectively, with each detection unit outfitted with with 18 digital optical modules. The photomultipliers in the optical modules detect Cherenkov light induced by charged particles in water, with the final goal of using the spatial and temporal information in data to identify neutrinos interacting near the detector. KM3NeT/ARCA is optimized for the search of astrophysical neutrino sources in the range of TeV to PeV; whereas KM3NeT/ORCA is used to study the neutrino oscillation phenomena in the 1-100 GeV energy range.

The results obtained from the data collected using various configurations of the KM3NeT/ORCA detector, corresponding to 5% to 15% of the final instrumented volume and 1.5Mton-years exposure are reported in this contribution. By studying the oscillation of electron and muon neutrinos produced in the atmosphere, a measurement of the tau normalisation factor, defined as the ratio between the number of observed and expected tau neutrinos, and their charged-current cross-sections are discussed. The event reconstruction, selection and analysis methods and future perspectives are also described.