Denver police say they found rocks, bricks and sticks stashed around the city that may have been placed there by people planning violence during the Democratic National Convention.

Police spokesman John White said Tuesday that the discovery and confiscation of the objects may have helped officers keep last week's convention relatively peaceful. He didn't elaborate on the discoveries.

Authorities say 152 people were arrested during a six-day period leading up to and including the DNC.

By contrast, 286 people were arrested on Monday alone during an anti-war demonstration in St. Paul, Minnesota, where Republicans are meeting this week. Authorities say a few of the 10,000 protesters broke windows, slashed tires and harassed delegates.

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