AzCDL) have fought against a number of proposals that would make you a criminal if any "child" accessed your gun and hurt themselves or another, but none even became law.
Looking through my notes, the last attempts were HB 2430 and HB 2431 back in 2008 (they never became law). You can read about them in our January 2008 newsletter .
Since they never became law, that means there are no specific laws deaing with the issue. However, I'm sure there are statutes that can be used to punish morons who leave loaded guns unattended around kids resulting in tragic outcomes.