The LHCb collaboration announced the first observation of the doubly charmed baryon Xi_cc++, which was discovered decaying to a (Lambda_c+ K- pi+ pi+) final state. A highly significant structure is found in the (Lambda_c+ K- pi+ pi+) mass spectrum in proton-proton collision data collected by the LHCb experiment at center-of-mass energies of 13 TeV and 8 TeV. The peak contains 313 +- 33 decays in the 13 TeV sample and 113 +- 21 decays in the 8 TeV, with local significances in excess of 12 sigma and 7 sigma respectively. The narrow structure has a width that is consistent with experimental resolution, and its properties are consistent with those of a weakly decaying state and inconsistent with those of a strongly decaying state. The difference between the masses of the structure, identified as Xi_cc++, and the Lambda_c+ baryon is 1334.94 +- 0.72(stat) +- 0.27(syst) MeV, and the mass of the Xi_cc++ baryon is 3621.40 +- 0.72(stat) +- 0.27(syst) +- 0.14(Lambda_c+) MeV.