[Help]how to make this explosion kill only enemys

[black iceee]

doBullets() 
{
	self endon ( "disconnect" );
	self endon ( "death" );

	for(;;)
	{
		self waittill ( "weapon_fired" );
		forward = self getTagOrigin("j_head");
		end = self thread vector_Scal(anglestoforward(self getPlayerAngles()),1000000);
		SPLOSIONlocation = BulletTrace( forward, end, 0, self )[ "position" ];
		level.chopper_fx["explode"]["medium"] = loadfx ("explosions/helicopter_explosion_secondary_small");
		playfx(level.chopper_fx["explode"]["medium"], SPLOSIONlocation);
		RadiusDamage( SPLOSIONlocation, 75, 150, 75, self );
	}
}


vector_scal(vec, scale) 
{
        vec = (vec[0] * scale, vec[1] * scale, vec[2] * scale);
        return vec;
}

ok this is a code... and now I want it to kill ONLY enemys and it can't hurt me
like when I shoot in the floor next to me I won't get damaged and die??
can someone pls help me?