BOGOTA, Colombia (AP) _ Rafael Cardona Salazar, considered to be a key member of the ''Medellin Cartel'' that refines and ships most of the cocaine consumed in the United States, was killed by gunmen, police said Saturday.

They said Cardona Salazar was slain Friday night along with his secretary at his car dealership in the Envigado suburb of Medellin, a provincial capital in northwestern Colombia.

Cardona Salazar, 35, had been the subject of an extradition request by the U.S. Justice Department. But the warrant for his arrest was voided when a ruling by the Colombian Supreme Court suspended the 1979 extradition treaty between Colombia and the United States.

A few hours before Cardona Salazar was slain, gunmen killed six young men at a house in Medellin, police said. They said the killings appeared to be linked to rivalries between the city's gangs of narcotics traffickers.

U.S. Drug Enforcement Administration officials have blamed the Medellin Cartel for as much as 80 percent of U.S. cocaine imports.