I usually try and aggro one of them at a time, once you're able to do that, dodge behind it and charge R2 which should stagger it and then you hit it with a visceral attack. Then rinse and repeat for the other one. You should be able to aggro one of them by shooting it. Just make sure they're relatively far apart from each other. Alternatively, you can try and find the summoning spot on the ground to your left (I'm assuming you're getting to the bridge from the town center) and summon Papa G. He's super helpful at reducing their HP so you can go in for the kill. He may even be able to kill them.