Nearly three-dozen people were arrested Thursday on federal charges related to a sprawling drug operation in Northwest Washington that authorities said distributed heroin and cocaine throughout the region.

The indictments, unsealed Thursday, charged 29 people with conspiracy to distribute and possess with intent to distribute illegal drugs, among other charges.

The law enforcement operation, officials said, included arrests at 31 different locations in the District, Prince George’s and Montgomery counties, Richmond and one in Georgia. In all, officials said they seized about $100,000 and 13 firearms, in addition to the drugs.

The arrests were the result of a drug-trafficking investigation that authorities said uncovered a far-reaching drug operation along the Georgia Avenue corridor and other parts of the Washington area.

U.S. Attorney Ronald C. Machen Jr., in a news release, called the takedown one of the largest in recent D.C. history.

“We have made a major dent in the supply of heroin and cocaine that would have been distributed in Washington,” D.C. Police Chief Cathy L. Lanier said in a statement.

If convicted, 31 defendants face sentences of up to life in jail, and three others face up to 40 years in prison.