Recently, the IceCube collaboration reported an unprecedented discovery of a high-energy muon neutrino event coincident with a multiwavelength flare from a blazar, TXS 0506+056. We show that the high-energy neutrino event can be interpreted by the inelastic hadronuclear interactions between the accelerated cosmic-ray protons in the relativistic jet and the dense gas clouds in the vicinity of the SMBH. Such a scenario only requires a moderate proton power in the jet, which could be much smaller than that required in the conventional hadronic model which instead calls upon the photomeson process. Meanwhile, the flux of the multiwavelength flare from the optical to gamma-ray band can be well explained by invoking a second radiation zone in the jet at a larger distance to the SMBH. In our model, the neutrino emission lasts a shorter
time than the multiwavelength flare so the neutrino event is not necessarily correlated with the flare but it is probably accompanied by a spectrum hardening above a few GeV.
