The Norwegian police think the two attacks are linked. The PM was supposed to attend the youth camp today. Whether that has anything to do with the timing is not clear. The Telegraph has a timeline and the Global Jihad terror group has claimed responsibility.
The BBC says that it has been confirmed that the gunman has been arrested and that he is Norwegian, whatever that might mean in the circumstances.
Norway's Justice Minister says that his information is that the arrested man is Norwegian but he (the Minister) does not know much else about him (the gunman). Reuters also points out that at present it is hard to tell exactly who is responsible for either or both the attacks, with pointers to both Islamists and possible right-wing extremists though there are claims by extremists that this is a "warning" to Norway and other European countries.