Two to the chest, one to the head (with the 9mm sidearm.) Also known as the Mozambique Drill.
However, I'd hesitate on a Mozambique Drill with four bad guys. That's 12 rounds total, but my house gun is a Glock 26 with 10 rounds. I carry a Glock 19 15 round magazine on the belt for a reload, but I can't speed load in 1.2 seconds like an IPSC shooter.
I can't speed load in 1.2 seconds like an IPSC shooter. You can if you just practice. Look up drills on tactical and emergency reload. Dry fire practice until you can do it in the dark. Practice indexing. 1.2 seconds is enough to draw and shoot 2 rounds, more than enough time for an emergency reload.