Legally speaking, I can't say 100%, but common sense and a basic grasp of typical laws and regs would suggest that, assuming it was simply Truck A pulling Truck B out of a ditch, while facing against traffic, causing Truck C to swerve, obviously it's Trucks A/B at fault. Now...if they clearly had their intentions marked or signaled, such as any sort of flashing lights, caution lights, or someone standing up the street to signal on-coming traffic, THEN it gets a bit more complicated. The truck in the ditch has to be pulled out, and chances are it was not going to happen without taking up a lane of traffic, therefore if they had some sort of warning for oncoming traffic, which Truck C missed due to some sort of negligence, then it may indeed be Truck C At Fault.
If you hit another vehicle then you are at fault. It does not matter what you were doing at the time.
when you get in an accident with another vehicle and you both receive damage to the front of you vehicle.
Only if it is moving forward and tide to the truck. Whether or not it is legal is another question. Pulling another vehicle is illegal in most states.
When you cause an accident that damages another vehicle or hurts someone
Most insurance companies will instruct you to call them first when you have an accident, unless there are injuries. You should call the police to get an accident report.
When you cause an accident that damages another vehicle or hurts someone
A single vehicle accident where a car leaves the road and rolls over or hits something ? Or a collision such as a car running a stop sign and hitting another vehicle?
Impact; collision; crash; accident
Avoid motor-vehicle accident
Avoid motor-vehicle accident
Underinsurer or uninsured Property damage coverage pays for damage to your vehicle if another vehicle is at fault for the accident but is uninsured or underinsured.
If a vehicle is pulling into roadway from driveway, the vehicle pulling out is at fault.