Oslo authorities said Sunday that an explosion at the U.S. embassy overnight may have been an act of terrorism, though other causes are also being investigated.
The blast, which caused no injuries and minor material damage, occurred around 1:00 am (0000 GMT) at the entrance to the embassy's consular section.
Police said an "explosive device" had caused the blast that targeted the embassy, but did not provide any other details.
Norway's Prime Minister Jonas Gahr Store called the incident "very serious and completely unacceptable". In a statement, he said he had spoken with the head of the U.S. embassy in Oslo on Sunday.
Shattered glass could be seen in the snow outside the building's entrance, as well as cracks in a thick glass door. Overhead lamps dangled from wiring, and there were black marks on the ground at the foot of the door, presumably from the blast.
