Deputy Attorney General Sally Yates said Wednesday that authorities are trying to take the most dangerous criminals off the streets. (Evelyn Hockstein for The Washington Post)

U.S. marshals nabbed more than 8,000 fugitives in a six-week blitz against serious, violent offenders in select cities across the country, authorities announced Wednesday.

Dubbed “Operation Violence Reduction 12,” the effort targeted the most serious criminals — those with warrants for crimes like murder, sex offenses and kidnapping — in a dozen cities that had seen recent upticks in crime. Between Feb. 1 and March 1, the marshals, working with local authorities, cleared 9,613 warrants, made 559 homicide arrests and seized 71.52 kilograms of drugs, authorities said.

“This took a whole lot of planning, and this was not an easy task,” Deputy Attorney General Sally Yates said.

Yates said the initiative was “not a dragnet-type operation,” but rather a “focused” effort to take some of the country’s most dangerous criminals off the streets. She said officials combed through warrants to identify the most serious cases in the chosen cities — among them D.C., Baltimore, Chicago, New Orleans and Brooklyn, N.Y. The average suspect, she said, had seven prior arrests and three prior convictions for violent offenses.

Baltimore Police Commissioner Kevin Davis said 148 fugitives were picked up in Baltimore as part of the operation, including 23 wanted for murder. He highlighted in particular the arrest of Carl Cooper, a suspect in the shooting and wounding of a 90-year-old woman and her 82-year-old brother. Cooper, Davis said, was firing at a rival drug dealer when the shots hit the unsuspecting pair on their way to buy sandwiches.

“Thanks to our U.S. Marshals Service,” Davis said, “we captured him in North Carolina.”