The incidents prior to the coup were growing protests against Chavez's heavy-handed approach to politics (which he has unfortunately continued since regaining power), which culminated in violence and gunfire between pro-Chavez and anti-Chavez protestors on April 11, 2002. There are conflicting reports about who was responsible (the pro-Chavez protesters say they were shooting back at snipers who were shooting at them, the anti-Chavez protesters say they were fired upon unprovoked), but the result was that military leaders seized Chavez, threw him in jail, and asked for his resignation on the condition that he would be exiled, otherwise he would be tried for the deaths of the protesters. Chavez said that he would resign only under the condition that his vice president would succeed him and the government would continue. The military leaders publicly proclaimed that Chavez had resigned, and put businessman Pedro Carmona, not Chavez's vice president, in charge. Carmona and other coup leaders had visited the White House on multiple occasions in months and weeks prior to the coup to visit Special Envoy to Latin America Otto Reich, and the U.S. was the only foreign government to immediately recognize the authority of the new leader.
But Carmona began his short term of office by abolishing the Venezuelan constitution, dissolving the National Assembly and the Supreme Court, and even changing the name of the country. This did not make the Venezuelan public or the military happy, and Carmona was quickly forced to resign in favor of power being briefly turned over to vice president Diosdado Cabello until Chavez was returned to office a few hours later. The total duration of the alternative government was about 47 hours. Carmona and his team went into exile.
It certainly looks like the CIA was involved. Otto Reich founded the Office of Public Diplomacy for Latin America and the Caribbean at the State Department, which engaged in covert propaganda activities before being declared illegal by the U.S. Comptroller General in 1987 for engaging in "prohibited, covert propaganda activities, beyond the range of acceptable agency public information activities." Reich was also involved with Col. Oliver North during the Iran-contra scandal. Both of these appear to indicate Reich being directly involved with the CIA.