We have measured the factorial moments up to fifth order, as well as the second-order normalized differential factorial moments, both as a function of the difference of transverse momentum (Δp T ) in π + p and K + p collisions at 250 GeV/c. The second-order differential factorial moments for like-charged pairs reveal a strong increase with decreasing Δ T . In a small central rapidity window, this increase is described by a simple power law. If interpreted as originating from Bose-Einstein correlations, such a behavior indicates a power-law structure of the transverse spatial distribution of the particle source.