HAMBURG, Germany - Police clashed with activists at a demonstration Tuesday against security plans for the upcoming G8 summit in Germany.

Police arrested 21 people at the Hamburg demonstration, the BBC reported.

About 4,000 people marched in a protest over the tight security planned for the June 6-8 G8 summit in the northern German seaside town of Heiligendamm.

The BBC reported that police used water canons and batons against the crowd, while demonstrators threw rocks and bottles.

A security fence has been built around the resort where the summit is scheduled and protests are prohibited inside the barrier.

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