It depends on the cause.

1. The AI chooses, of its own volition, to kill people. It is likely that by the time AI has this level of control and intelligence, it is too late to stop it.

2. A malicious person uses AI to cause a terrorist event or some other kind of catastrophe. This is more likely. The AI in this scenario is more like a tool. Attributing AI to the cause might be difficult, but it's likely that any new bioweapons which emerge in the next 1-2 years are likely developed by AI.

I think we should all hope that 2 happens before 1, but it doesn't feel good to hope for a catastrophe.