Gonna be honest the first time it got me I was fighting something in melee, so I couldn't tell you if it prioritized him or me, it was firing at him before I got in range and it feels like it shot at him after I noticed what was happening and backed off (meaning the gray dwarf shaman iirc was closer).

For all I know though it was shooting at him the whole time and I just got in the way, but after it was dead it kept shooting at me.