In this case I think most jurisdictions would treat the AI as just another tool or piece of equipment.

If you asked a similar question about who would take the blame if a piece of X-ray equipment was not working properly and caused some form of harm, the liability might fall on the X-ray machine manufacturer who guaranteed a certain level of accuracy, or it might fall on the hospital that procured the (potentially unsafe/certified) equipment. It might also fall on the physician who wasn't following the proper protocol for using the equipment.