A search was under way for another lawmaker and at least 10 more party members.
It is the first time that the leader of a political party and members of Parliament have been arrested in Greece since the fall of a military junta in 1974.
Less than two weeks ago, the murder of an anti-fascist Greek singer, the rapper Pavlos Fyssas, 34, ignited an uproar throughout Greece after the suspect claimed to be a Golden Dawn supporter.
The public outcry over the killing put substantial pressure on the government to move ahead with an investigation of the party.
On Saturday, Nikos Michaloliakos, Golden Dawn’s leader and a member of Parliament, was charged with forming a criminal organization. With a defiant expression on his face, Mr. Michaloliakos raised his cuffed hands as he was escorted by police officers. Another arrested lawmaker, Ilias P. Kasidiaris, shouted as he was led away: “Nothing will bend us! Long live Greece!” Other arrests followed.
The police had not yet released details of the criminal charges, but they include murder, attempted murder and blackmail, according to a court official. The party has denied any role in the killing, and the police had not said what evidence they have linking the arrested party members to specific crimes.
Since 2012, when it gained seats in Parliament, Golden Dawn has engaged in a campaign of intimidation against immigrants. In April, the Council of Europe’s human rights commissioner described it as “a neo-Nazi and violent political party” and urged that it be banned under international human rights treaties, but the arrest of elected lawmakers is a rare step for any European democracy.
The move may curb Golden Dawn’s influence, at least for now, especially in Parliament, where the party holds 18 seats after elections last year during a volatile moment when Greece was on the precipice of exiting the euro zone.
Nonetheless, the disenchantment stoked by the economic crisis that helped propel Golden Dawn’s rise is unlikely to fade anytime soon.
“As the country is mired in its worst economic crisis in modern history, support for extremist and antiestablishment parties is likely to remain high in the coming years, regardless of the future of Golden Dawn as a political party,” the geopolitical intelligence, economic and political firm Stratfor said in an analysis.
Human rights groups say Golden Dawn, whose members perform Nazi salutes at rallies and meetings, has systematically terrorized immigrants, while the police have looked the other way. The aggressive acts include the beating of immigrants with clubs and shields bearing swastikalike symbols or with wooden poles draped in the Greek flag.
Golden Dawn was established in 1987, and its influence has grown in recent years in tandem with the country’s economic hardship. Offering promises to restore jobs and order, the party’s members also espouse nationalistic and xenophobic stances, appealing to marginalized Greeks in areas populated by a rising number of unemployed immigrants, mostly from Pakistan and North Africa.
Those arrested early Saturday also included the lawmakers Nikos Michos, Ilias Panagiotaros and Yiannis Lagos, and also Giorgos Patelis, the leader of the party’s local chapter in Nikaia, a gritty Athens suburb that is one of Golden Dawn’s biggest strongholds, and 12 other party officials.
The immunity usually enjoyed by Greek members of Parliament is automatically lifted in the case of felonies. For lesser charges, a vote has to be held in Parliament.
In addition, two police officers connected with the organization were caught up in the sweep, a sign that a parallel crackdown is intensifying against parts of the police, long thought to have been infiltrated by members or sympathizers of the group.
Niki Kitsantonis contributed reporting.