New Delhi, March 9 -- Police in Norway were investigating an explosion early Sunday outside the U.S. Embassy in Oslo, the capital of the Scandinavian country, officials said.

No injuries were reported. Police received reports of a "loud bang" or explosion around 1 a.m., Oslo police said in a news release.

The explosion was caused by some sort of incendiary device, according to Frode Larsen, leader of the Oslo police joint unit for investigation and intelligence. Investigators believe the embassy was the target and are searching for the perpetrators and their motive.

Larsen said the embassy's entrance had damage, but no arrests have been made.

"We are early in the investigation, but we are working based on multiple hypotheses," Larsen ...