Identifying the sources of extragalactic neutrinos is one of the foremost challenges in the astrophysics and multi-messenger fields. Amongst the most promising neutrino candidate sources there are blazars, active galactic nuclei hosting a relativistic jet pointed towards us. In this seminar, I present a study that provides evidence for a spatial correlation between high-energy (>100 TeV) IceCube neutrinos and a well-defined sample of blazars in the southern celestial hemisphere. The probability for the genuineness of such correlation is as low as 2 x 10^-6 (~4.5 sigma, post-trial), suggesting that it is highly unlikely to arise by chance. The study pushes forward a subset of objects as highly likely extragalactic neutrino sources and, hence, cosmic rays PeVatron accelerators.