Hundreds of federal agents and local police rounded up nearly 30 alleged gang-members Wednesday in Woodbridge, Alexandria, Maryland and D.C.

The raids capped months of investigation led by the federal Bureau of Alcohol, Tobacco, Firearms, and Expolosives into drug-dealing, gun-trading and murder by the "Bloods," a notorious gang that started in California.

The US Attorney's Office in Alexandria says agents seized thousands of grams of cocaine, crystal meth, and heroin -- along with more than 70 firearms.

Click here to view the full list of the 28 arrested.

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A spokesman for the Bureau of Alcohol, Tobacco, Firearms and Explosives said the "round-up" was on-going mid-Wednesday afternoon.

Lloyd Burton said it focused on "local gangs" and "violent criminals" in Northern Virginia, with some operations spilling over into D.C. He said the suspects do not belong to the notorious MS-13 gang, he said it's another group.

He said the ATF had been investigating for some time, but needed help from other police agencies as it swept in to arrest suspects. He said some firearms were involved.

According to Kadia Koroma, spokeswoman for the FBI Washington Field Office, the court-authorized law enforcement activity in the D.C region and involved multiple federal, state, and local agencies.

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