Sad news for the white rhinoceros

I just read in the news that poachers killed the white rhinoceros Vince in the Thiory zoo. This is the first time poachers committed their crimes in a zoo, in Europe. They managed to get away with one of his horns. Poachers are no longer just confined in Africa. The horns must be so priced that poachers are willing to take the risk to break into the zoo. The population of these animals in the wild are menaced. Now, even the zoos can't protect them.
We have visited this zoo twice and this is such a sad news. :(