Coherently pumped far-infrared ring lasers with pump and laser fields having crossed linear polarizations are known to exhibit type-I intermittent dynamics [D. Y. Tang, M. Y. Li, and C. O. Weiss, Phys. Rev. A 46, 676 (1992)]. We study here a homogeneously broadened four-level model for these laser systems. For a small range of parameters our model also shows a type-I intermittency route to chaos, but a complete agreement with their experimental results is not achieved. © 1994 The American Physical Society.