Two of the four Blackwater-affiliated contractors involved in a civilian shooting incident in Kabul earlier this month have fled to the U.S. in order to avoid possible prosecution from Afghan authorities, according to their attorney.

The four men worked as military trainers for Paravant LLC, an affiliate of Blackwater Worldwide, whose parent company is now called Xe after a recent name change. Paravant was assisting Raytheon Co. on a Defense Department contract.

Armed...