Authorities in Oslo are investigating an explosion that struck the United States Embassy in Oslo early Sunday morning.

According to police, the blast occurred around 1 a.m. local time and impacted the embassy’s consular entrance. Officials said the explosion caused only minor damage and no injuries were reported.

The incident commander at the scene, Mikael Dellemyr, confirmed that police are working closely with embassy staff while searching the surrounding area for any potential threats to personnel or nearby residents.

Witnesses in the neighborhood reported being awakened by a loud blast.

“I was sleeping and was woken up by the explosion. It was really powerful,” a nearby resident told local media, adding that smoke could be seen coming from the embassy building shortly after the incident.

Police said investigators have preliminary suspicions about what may have caused the explosion but declined to release further details because the case remains an active investigation.

Officers also conducted searches in the area to ensure there were no additional dangers, and authorities said nothing further was discovered during those checks.

The Oslo Police District has not yet announced any suspects or confirmed the cause of the explosion. The embassy and local authorities are continuing to monitor the situation as the investigation moves forward.