This open-topped jaguar exhibit had a 3 year-old boy fall into it and the child was bitten by the zoo's 2 jaguars. The little boy is in critical condition and hopefully he pulls through and survives.
It is a very sturdy railing and the edge of the jaguar exhibit also has a mock-rock wall. I honestly think that sometimes parents become complacent and as someone with little kids I'm always extremely aware of the dangers around enclosures with potentially harmful animals inside.