Law enforcement SWAT teams using police dogs raided homes in Northern Virginia and Florida in the predawn hours yesterday, ending what they said was a massive drug trafficking operation that "relied on threats, intimidation and other acts of violence."

Federal law enforcement officials yesterday charged 16 persons from the Washington area and Florida with 124 drug, firearms and other violations in connection with a drug ring that allegedly distributed millions of dollars worth of cocaine, hashish and marijuana throughout Northern Virginia during the last 15 years.

The ring, which allegedly purchased the drugs in Florida, employed more than 50 persons and earned more than $10 million during the 15-year period, according to an affidavit filed yesterday in U.S. District Court in Alexandria.

Shortly before 5 a.m. yesterday, law enforcement officials using police dogs and helicopters raided neighborhoods in Northern Virginia and Florida, eventually arresting 11 persons, according to Robert J. O'Leary, a spokesman for the federal Drug Enforcement Administration. Authorities said they have issued warrants for the arrests of five other persons indicted on the drug and firearms charges.

O'Leary said the grand jury handed down the indictments last month, but they were sealed pending yesterday's arrests.

Four federal agencies and the Fairfax County Police Department participated in the three-year investigation that began with a few routine drug purchases by undercover law enforcement officials in Fairfax County. The Organized Crime Drug Enforcement task force organized by President Reagan in 1982 coordinated the operation.

O'Leary said the operation allegedly distributed hundreds of pounds of cocaine and tons of marijuana and hashish in Northern Virginia. He said two-thirds of the charges involved illegal possession of firearms including Ruger bolt-action rifles and Beretta pistols.

The investigation included wiretaps, undercover purchases, surveillances and extensive grand jury work, O'Leary said.

Four of the persons were charged under a federal law known as the kingpin statute, which law enforcement officials use in cases involving continuing criminal operations, O'Leary said. Persons convicted under the statute are subject to lifelong imprisonment without parole, he said.

O'Leary said no drugs were seized in the raids, but said officials are seeking court authority to seize assets, including houses, automobiles, cash and firearms, owned by those arrested.

Those alleged to be the major participants in the operation are Stephen C. Melnicoff, 40, of Middleburg, William R. Thompson, 38, of Great Falls, Steven T. Haag, 33, of Annandale, and Horacio Montoya, 46, of Miami.

Other Washington area residents named in the indictment were Rene Doucet, 25, and John E. Finks, 29, of Great Falls; Kim E. Minis, 32, Mary E. Minis, 28, and Eric P. Sloman, 25, all of Reston; John M. Powell, 28, and Wilbert D. Sprouse, 36, both of McLean; Debra Saxman, 29, of Middleburg; and Christopher Williams, 46, of the District.