Police in Maine's largest city have charged a Norwegian man with making threats against officers via email and Twitter.

City police say 28-year-old Espen Brungodt was unarmed and offered no resistance when he was arrested at a Portland hotel Wednesday afternoon on federal charges of transmitting threatening communications.

The Portland Press Herald reports that the threat came from someone who said it was "time for more police to die." The email sender threatened to "shoot and kill" officers.

Police treated the threats seriously. A parking garage was checked for explosives and a courthouse was evacuated.

Brungodt's hometown wasn't released. Police say he entered the U.S. through Boston on July 26 with family members, who were unaware of his threats.

There was no indication if he had a lawyer who could comment on the accusations.