Norwegian police are investigating an explosion outside the United States Embassy in Oslo after a blast damaged part of the diplomatic compound early on March 8.

Authorities said they received reports of a loud explosion around 1 a.m., prompting a large emergency response that included police units, bomb technicians, drones and helicopters. Investigators later confirmed that an incendiary device had detonated outside the embassy’s consular section.

The blast caused minor structural damage to the embassy entrance, but officials said no injuries were reported. Police believe the embassy may have been the intended target and are examining several possible motives while searching for suspects. Norway’s Justice Minister condemned the incident and said authorities are treating it with the utmost seriousness. The country’s domestic security service has joined the investigation but has not raised the national terror threat level.

The explosion comes during a period of heightened international tension related to the conflict involving Iran, Israel and the United States, prompting increased security around diplomatic facilities. Police say the investigation is ongoing and have appealed for witnesses or information about anyone seen near the embassy around the time of the blast.