Police say a preliminary investigation shows a man broke into the west front entrance around suppertime on Monday and was in the building's basement.
A government official says the intruder was yelling that he was King Edward.
Officers found a shirtless 24-year-old man behaving in an irrational manner and carrying items believed to have been taken from the legislature gift shop.
Police say the man was arrested and taken to hospital for observation.
Damage to the door is expected to cost about $2,000 to repair.
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