If an autonomous vehicle kills someone, who is liable?

While we have all been getting excited about the prospect of autonomous vehicles a couple of issues seemed to have been overlooked, but now it seems the legal community is addressing a big one; liability.
The technical challenges of autonomous vehicles are massive. Latency needs to almost non-existent, coverage needs to be almost ubiquitous and the AI components need to be almost perfectly intelligent while also demonstrating almost human like logic and context. These very complex problems, but