ST. PAUL (Reuters) - Police in riot gear battled hundreds of protesters with pepper spray and smoke bombs and arrested 130 people on Monday at the start of the Republican presidential convention.

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Officers on horseback, motorcycles and bicycles chased a group of rock- and bottle-throwing protesters who broke off from a peaceful march of up to 10,000 people through downtown St. Paul.

Protesters, some hiding their faces with black kerchiefs, smashed shop windows, overturned garbage cans and vandalized police cars. Some pushed a flaming dumpster into a car with police in it, officers and witnesses said.

Police said 130 people had been arrested. The charges ranged from trespassing to property damage and assault, a spokeswoman said. One officer was punched in the back and another was overcome by the heat, St. Paul police chief John Harrington said.

Demonstrators marched from the Minnesota state capitol to the heavily barricaded Xcel Center, where John McCain accepts the Republican presidential nomination later this week. Public safety officials put the crowd at 8,000 to 10,000.

Most protesters demanded an end to the Iraq war, although their causes ranged from increased rights for immigrants to changing U.S. policy in Ethiopia. T-shirts backing McCain’s Democratic rival Barack Obama were common.

Some carried signs supporting politicians like Republican Ron Paul, a libertarian-leading Texas congressman and former McCain opponent, and Ralph Nader, a consumer activist running for president as an independent.

The march wound past bus stops where advertisements from the Democratic National Committee showed Republican President George W. Bush and McCain hugging with the slogan, “Does this look like change to you?”

The Republicans scaled back their convention festivities on the first day, aware that they risked a political backlash if they were shown celebrating as Hurricane Gustav pounded the country’s Gulf Coast.

Convention organizers held a truncated business-only session on Monday and scrapped a planned speech by Bush.

The absence of the president, whose nationwide approval ratings hover around 30 percent, did not deter the crowd.

Carrying a sign that said, “Hold Bush accountable,” Gary Frazee from neighboring Minneapolis said he suspected that the president was using the hurricane as an excuse to stay away.

“Why would he show up? There’s no love for him here,” he said.

Mary Gleason, a retired church musician from Minneapolis, said Hurricane Gustav “kind of worked in their favor. They won’t have to wait for Bush and (Vice President Dick) Cheney to say something stupid.”

As the protesters marched around the convention site, about 100 McCain supporters waved signs saying, “Let our soldiers win,” drawing spirited chants from the marchers, including “War is not pro-life.”