CARACAS, Venezuela — A huge crowd filled the streets of Venezuela's capital on Sunday cheering for opposition candidate Henrique Capriles, waving flags in a show of support one week before the country's hotly contested presidential election.

Capriles waved from a truck that rolled through the vast expanse of supporters. The crowd filled a downtown avenue and appeared to surpass 100,000 people.

The authorities didn't provide a crowd estimate.

While President Hugo Chavez was leading weekend rallies elsewhere in the country, authorities were investigating the killings of two men in a shooting that erupted during an opposition campaign caravan in western Barinas state on Saturday.

Justice Minister Tareck El Aissami said in a message on Twitter on Sunday morning that a suspect was arrested in the double murder, but he didn't immediately identify the suspect.

Opposition lawmaker Julio Cesar Reyes said on Saturday that a group of Chavez's supporters blocked the caravan and people on both sides were arguing when a gunman appeared and started shooting.

Opposition officials said both men killed were participants in the motorcade of Capriles supporters.

Chavez, meanwhile, rallied thousands of supporters on Saturday in Guarenas, a town east of Caracas, telling them: "It's impossible for us to lose." The crowd chanted: "Ooh, Ahh, Chavez won't go!"