Even if they knew, if they had themselves been moral and decided to stop all travel, it would've been fair to say we are all responsible. They did not do that. Sure all the countries are at fault too definitely (me, as an Indian, included) but doesnt take away the fact that Chinese authorities downplayed this and led to the spread. No matter how you put it and the moment it had spread world over, stopped flights to China to stop spread.
Sorry, all governments are to blame here, for sure (these deaths cant be justified) but China and to a large extent WHO are in the blame here too. Majorly.