More than a dozen arrests, police blockades and property damage marked the first day of the Republican National Convention, which was surrounded by protesters despite its abbreviated schedule.

Between 8,000 and 10,000 protesters marched from the Minnesota state Capitol to the Xcel Energy Center, herded by hundreds of police officers decked out in full riot gear with gas masks, batons, armor and helmets.

The mayhem delayed hundreds of delegates who arrived at overwhelmed security barriers for Monday’s 3 p.m. opening ceremonies. And the Capitol Police had trouble getting Members of Congress to the entrances, stymied by new road closures and police blockades.

Senate Sergeant-at-Arms Terrance Gainer said the blocked-off streets and dense downtown area made it tough for the Capitol Police officers who are guarding Members this week.

“It’s been frustrating for some of the Members, as it has for everyone,” he said Monday afternoon. “Everybody needs to be patient, and they’re getting in there slowly but surely.”

The scene was far different from the Democratic National Convention last week, where protesters were scarce and groups of bored police hung out on street corners. In St. Paul, even the city-designated “public viewing area” was filled with people — a stark contrast to the abandoned demonstration zone at the Democratic National Convention.

Crowds of protesters rallied against the Iraq War and presumptive presidential nominee Sen. John McCain (R-Ariz.) — most holding signs and some in costume — and became somewhat of a spectacle for St. Paul residents and visitors, who watched from sidewalks and parks.

Police officials wouldn’t say how many officers were on the scene, but as many as 50 crowded some street corners. About 150 National Guard soldiers also descended onto the street in two Humvees and several buses, helping police control the crowds.

“This is not a surprise. This was part of the plan,” Capt. Anna Long, a spokeswoman for the National Guard, said on Monday afternoon. “It’s just the amount of people. Our mission in this is to free up the local officers.”

Despite Hurricane Gustav, all the National Guard soldiers assigned to the convention stayed in St. Paul, Long said. About 3,500 police officers are in the city this week — most from out of town and some from out of state. On Monday, plenty were on hand to control protesters and block off streets.

“It seems like it’s mainly a show of force,” said Steve Clemens, a volunteer with the Minnesota Peace Team, which aims to prevent violence between protesters and police. “I think they’re just kind of organizing themselves, but it seems to be a heavy presence.”

Most protesters on Monday were peaceful, but others wreaked havoc, smashing windows, slashing tires and overturning garbage bins.

Police arrested 13 people — seven misdemeanors, four felonies and two gross misdemeanors. Police officials had not released the specifics of the charges or the circumstances of the arrests by press time, though several news agencies reported that police used tear gas and pepper spray to disperse one group.

As the large crowds traveled through St. Paul’s downtown, police blocked off cross streets and entrances to the Xcel Center. Lines stretched around street corners, while riot police blocked the most convenient routes.

The action got close to the Crowne Plaza Hotel, where some of the Members are staying, but Gainer said no Members were hurt or targeted by protesters. The mayhem surprised some new Capitol Police officers, he said, who are used to the mostly peaceful protests on Capitol Hill.

“I think people are surprised at that level of discontent,” he said. “For some of our new officers, much of this destructive behavior on the part of demonstrators is eye-opening.