The Λ + c K − mass spectrum is studied with a data sample of p p collisions at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 5.6 fb − 1 collected by the LHCb experiment. Three Ξ 0 c states are observed with a large significance and their masses and natural widths are measured to be m [ Ξ c ( 2923 ) 0 ] = 2923.04 ± 0.25 ± 0.20 ± 0.14 MeV , Γ [ Ξ c ( 2923 ) 0 ] = 7.1 ± 0.8 ± 1.8 MeV , m [ Ξ c ( 2939 ) 0 ] = 2938.55 ± 0.21 ± 0.17 ± 0.14 MeV , Γ [ Ξ c ( 2939 ) 0 ] = 10.2 ± 0.8 ± 1.1 MeV , m [ Ξ c ( 2965 ) 0 ] = 2964.88 ± 0.26 ± 0.14 ± 0.14 MeV , Γ [ Ξ c ( 2965 ) 0 ] = 14.1 ± 0.9 ± 1.3 MeV , where the uncertainties are statistical, systematic, and due to the limited knowledge of the Λ + c mass. The Ξ c ( 2923 ) 0 and Ξ c ( 2939 ) 0 baryons are new states. The Ξ c ( 2965 ) 0 state is in the vicinity of the known Ξ c ( 2970 ) 0 baryon; however, their masses and natural widths differ significantly.