A federal grand jury has indicted 20 Missouri residents for allegedly trying to sell at least a kilogram of heroin and other drugs.

A Monday release from U.S. Attorney Timothy Garrison's office says 16 of the 20 defendants were arrested Oct. 2 for purported drug trafficking dating as far back as 2011.

Most of the defendants are from Kansas City.

Roughly 200 law enforcement officers were involved in the arrests.

Investigators seized 23 guns, $75,000 in cash, and drugs including heroin and cocaine. Officers also say they found a bullet-proof vest and a ledger on a nightstand that appeared to document drug sales.