The security police warned of a “credible” threat of a terrorist attack within the next few days against targets in Norway by people connected with Islamic extremists in Syria. The attack was reportedly planned in Europe. Security measures have been stepped up, and both the City Hall and the Royal Palace in Oslo were closed to tourists as a precaution. About 50 Norwegians are thought to have traveled to Syria to fight, as have about 40 Finns, and some 80 Swedes are said to have joined jihadist groups in Syria.