OSLO, Norway -- The U.S. Embassy and an area of central Oslo were evacuated on Tuesday when a fake explosive device was mistakenly left beneath a vehicle trying to enter the compound, police said.

The discovery of the device by security guards also led to the evacuation of the royal palace, the halting of subway traffic in the area, and the cancellation of an international children's soccer game at nearby Voldslokka Stadium so police could use the field for helicopters.

The bomb scare and police search closed the entire area for several hours.

"The Oslo police bomb squad has removed the object and can confirm that it was a dummy bomb," police said in a statement. "The car has been used for an internal drill at the embassy, and the find can be connected to this."

Norway's monarch was not at the palace at the time, but people visiting it were evacuated during the security check.

The U.S. Embassy did not immediately comment about how the mistake had been made.

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