Tesla CEO Elon Musk: "Mark's understanding of [AI] is limited."

And by "Mark", he means Facebook CEO Mark Zuckerberg.

It all started on Sunday, when Zuckerberg blasted warnings against artificial intelligence (AI) as "pretty irresponsible" while he was taking questions in a Facebook live broadcast.

Referring to Elon Musk's recent comments on AI at the National Governors Association summer meeting, which warned that the technology poses a "fundamental risk to the existence of human civilisation" and has to be regulated, a Facebook user asked, "I watched a recent interview with Elon Musk and his largest fear for future was AI. What are your thoughts on AI and how it could affect the world?"

Zuckerberg responded, "I think people who are naysayers and try to drum up these doomsday scenarios — I just, I don't understand it. It's really negative and in some ways I actually think it is pretty irresponsible."

He said he was an optimist about AI, as it will be responsible for lifesaving services such as diagnosing diseases and driving cars.

The statement reached Musk on Tuesday, as he responded on Twitter:

Zuckerberg has not responded to Musk's latest tweet, but netizens have gone wild about it.