DENVER (Reuters) - Police in riot gear fired pepper balls and mace into a crowd of economic protesters in Denver on Saturday and arrested 20 after some people entered the grounds of the State Capitol, police said.

Denver Police Spokesman Lt. Matt Murray said about 2,000 demonstrators from "Occupy Wall Street" protests against economic inequality marched peacefully through downtown Denver, as they have done for the past several Saturdays.

But the situation heated up when protesters moved toward the Capitol. The Colorado State Patrol, which provides security for the statehouse, requested aid from Denver police when marchers entered the Capitol grounds, Murray said.

Someone then kicked over a police motorcycle, slightly injuring an officer, and kicked several other officers, he said. Police in riot gear moved in on the crowd, firing pepper balls and mace into the crowd, Murray said.

Murray said the seven arrests were for assault, assault on a police officer, disturbing the peace and disobeying lawful orders.

Thirteen more people were arrested when protesters attempted to erect a tent in a park across from the Capitol. Police took the tent down and protesters who interfered with police were arrested.

One protester was treated by paramedics at the scene after police physically restrained him.

"He was kicking at officers and was very intoxicated," Murray said.

Murray said once police removed the tent, most of the crowd dispersed and the situation calmed down.

(Editing by Greg McCune)

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