Cross sections for the (p, pn) reaction at a proton energy of 370 MeV have been measured with Sc45, Cr50, Cr52, Mn55, Fe56, Ni58, Co59, Cu65, Ga69, and Ga71 targets. All of the (p, pn) cross sections, except those for Sc45, Cr50, and Ni58, were found to be about 60 mb. No quantitative explanation could be found for these three divergent cross sections, all of which are lower than the others. Cross sections for (p, 2n) reactions on Cr52 and Fe56 were also measured. Calculations based on the (p, 2n)-(p, pn) ratio show that at least 85% of the (p, pn) reactions proceed by a pure knock-on mechanism.