HAMBURG, Germany - Thousands of people are taking part in a protest against the Group of 20 summit titled "G-20: Welcome to Hell," with authorities wary of potential violence.
Demonstrators gathered at a riverside plaza used for Hamburg's weekly fish market Thursday before setting off on a march through the city.
There were no immediate reports of significant trouble, though police said a few bottles were thrown. Police using loudspeakers also were calling on about 1,000 demonstrators to remove masks.
Hamburg has boosted its police with reinforcements from around the country for the G-20 summit, so that 20,000 officers are on hand to patrol the northern German city's streets, skies and waterways.
More than 100,000 protesters are expected in the city for the summit, according to police.