We present high spectral and spatial resolution spectroscopy of the nuclear starburst region of the galaxy NGC 253. Two slit positions, matching the major and minor axes on the galaxy, have been taken. These cover H-alpha and (N II) lines as well as the (S II) doublet. The attained resolution, together with good seeing conditions, have allowed the detection of line profile variations on the scale of arcseconds. The global kinematical features along the major and minor axes yield a lower limit to the total extension of the nuclear starburst of about 725 pc. The shape of the line profiles together with the observed structure of the velocity curves imply emitting region cells of about 160 pc, a size typical of OB associations in our galaxy. A detailed analysis of the incremental flux ratio (NII)/H-alpha leads to the conclusion that there are differences in the excitation conditions and/or abundances, that change with the velocity of the gaseous components. The evidence thus implies that the activity of the nuclear starburst of NGC 253 results from the joint action of several, coeval, well detached star forming centers, rather than a single super-massive one.