Grozny OMON fratricide incident
The Grozny OMON fratricide incident took place on March 2 , 2000 , when an OMON ( Russian special-purpose police ) unit from Podolsk , supported by paramilitary police from the Sverdlovsk Oblast in armored vehicles , opened fire on a motorized column of OMON from Sergiyev Posad ( Moscow Oblast ) , which had just arrived in Chechnya to replace them . 
<triplet> Grozny OMON fratricide incident <subj> March 2, 2000 <obj> point in time