Twenty accused street gang members were arrested on charges of running a sophisticated drug trafficking operation as part of a three-year undercover investigation, authorities said Tuesday.

Since the investigation began, 38 accused members of the Latin Kings street gang have been charged and at least 20 individuals — including several men believed to be top leaders — have been taken into custody on drug and weapons charges, U.S. Attorney Patrick Fitzgerald said during a news conference.

"We pretty much decapitated the Latin Kings on the South Side," said Andrew Traver, a special agent with the Bureau of Alcohol, Tobacco and Firearms, the main agency involved in the investigation.

The charges are included in 13 separate federal complaints filed or unsealed Tuesday.

Todd S. Pugh, an attorney for one of those arrested, Anthony "Loks" Compean, declined comment Tuesday evening. It wasn't immediately clear who was representing the others arrested.

In an unrelated case, federal agents and police from New York and New Jersey seized 1,045 pounds of Manhattan-bound cocaine valued at $42 million that was hidden in a tractor trailer and arrested six men on narcotics trafficking charges, authorities said Tuesday.

It was the largest cocaine seizure this year in the New York area, said special narcotics prosecutor Bridget G. Brennan.