Really hard to say if they got the private key, but it is really weird if they try to hack back the hackers?
Servers doesn't contained private key, and I believed that the hackers will keep in somewhere safe. So it is really mind boggling, if governments has the ability to track and seized the ransom, then by all means they can get to anyone.
Anyhow, this is clearly an cyber war now against those group of hackers who is targeting, anything, from universities to hospitals to private companies to demand huge amount of money in bitcoins.