EUGENE, Ore. -- Dozens of people linked to an Oregon drug trafficking network have been arrested by federal and state authorities, according to the Drug Enforcement Administration.

Officials said the sophisticated organization imported heroin, methamphetamine and cocaine from Mexico and then distributed it to Oregon, California and Washington.

An eight-month investigation led to numerous federal search and arrest warrants in the Eugene area Wednesday.

Officers said they found heroin, methamphetamine, marijuana and thousands of dollars in cash during their searches. They also arrested 31 people, whose court appearances were expected to begin Wednesday.

Authorities estimated 25 kilograms of heroin and 15 pounds of methamphetamine were distributed through the network on a monthly basis in the southern Willamette Valley.