This can be found at www.cnn.com

MAR DEL PLATA, Argentina (CNN) -- Protesters set one building on fire Friday and threw objects at police in the streets of this resort city as the leaders of 34 nations began the fourth Summit of the Americas.

Video showed flames and smoke on the bottom floor of one multistory building just blocks from the summit site.

CNN Producer Alec Mirian said that in response to the violence police officers showed up on motorcycles followed by officers on foot in riot gear.

Many of the protestors wore red bandanas and carried wooden sticks several feet long, while some had rocks. Some threw small explosives similar to Molotov cocktails.

Earlier in the day, Venezuelan President Hugo Chavez led thousands of protesters in a rally against President Bush's policies.

Chavez, who U.S. leaders have said is a source of instability in the hemisphere, condemned what he called U.S. imperialism while demonstrators opposed to the Iraq war and U.S.-led trade policies called Bush a "fascist" and a "terrorist."

Argentine soccer legend Diego Maradona also participated in the protest, wearing a T-shirt accusing Bush of war crimes. (See video of the protest -- :2

Chavez, a left-leaning populist, routinely denounces Bush as "Mr. Danger" and refers to the United States as "the Empire."

Bush was expected to see Chavez at the summit later in the day. At a brief news conference, Bush said he would be "polite."

He also said he viewed his participation in the summit as an "opportunity to positively affirm our belief in democracy and human rights and human dignity."

Bush said he was gratified by his meetings with leaders of several Central American countries, which he described as "young democracies" eager to implement a free trade agreement.

Bush's first meeting Friday was with leaders of nations that joined the Central American Free Trade Agreement. CAFTA was narrowly approved by Congress in July after an intense push by the White House.