Report back to guard com, proceed to investigate loh..if the
situation arise, if u have to fire, u got to fire ....besides..the
incident your describing is happening at nite...not too sure if
BMTC are using SAR 21s, with a M16 without LADs..shooting a black
mass running or hiding with 3 rnds..is going to be one hell of an
shootout man 
well the reason for IA Drill aka Immediate Action Drill, is to
respone to the situation ASAP.so given the above mentioned scenrio
u described,loading the magazine, shouting the ROE and shooting
should be almost instantnous ...