Go to the Police - and the dogs go ... nothing can go forward until the dogs are gone. Call animal control - whoever you need to call get them picked up and gone. Take photos of the crime scene - document... document... document...
Sadly, the dogs don't always "go" when this situation happens. On March 7th, three of my neighbor's pit bulls got loose, came
through my fence into my backyard and attacked my Lab, Conner. I heard the barking and got around there in time to see Conner on the ground with the three pits on top of him - one at his throat, one at his front legs, and one at his rear legs. I ran over there and tried to pull them off (and got bitten in the right arm and left hand in the process). My husband came around the corner with the shotgun, killed one, severely injured one, and the third got away.
A report was filed with (I thought) Animal control from the ER room of the hospital that night, but when I followed up on it, no report had been filed; only one with the Health Dept to verify rabies for the attacking dogs. Finally, Animal control came out to seize one of the dogs, but left the injured one with the owners. The court ruled that the dogs were dangerous animals and had to wear tags that stated that, but the seized dog was returned and the injured one is healing. I'm sure those tags are going to do a lot of good to the next pet...or horrors, child....they attack and severely injure or kill.
My dog is healing, but had multiple stitches (left front elbow ripped open, inside left front and inside right front slashed, multiple puncture wounds on both front legs, one all the way through rear thigh muscle and right ear, multiple puncture wounds around face and throat)
This is the second time these dogs have gotten loose and attacked a neighbor's dog - that one didn't survive the attack. I can't just turn my dogs loose in the backyard and go do something else - like feed the chickens. I stay right there the whole time they are out, with a shovel handy...just in case.
Edited to add:
My husband's greatest regret is that he didn't get a better shot on the one that survived, and had time to get a shot on the third one that got away.