A man leapt on stage and put a gun to the head of the leader of Bulgaria's ethnic Turkish party before security guards wrestled him to the ground during a televised conference on Saturday.
Ahmed Dogan, the leader of the Movement for Rights and Freedoms (MRF) escaped unscathed, and it was not immediately clear why the attacker targeted him at the party congress in central Sofia.
Television footage showed the man jumping out of the audience brandishing the gun which he pointed at Dogan's head. Security guards pulled him to the ground and he was repeatedly beaten and kicked by conference delegates.
Police said they arrested the attacker, a 25-year-old from the Black Sea town of Burgas, who was also carrying two knives.
Interior Minister Tsvetan Tsvetanov said the attacker tried to fire two shots but "most likely the gun misfired".
The liberal MRF party represents ethnic Turks and other Muslims who make up about 12 percent of Bulgaria's population of around seven million. Most Muslims in Bulgaria are not recent immigrants but are a centuries-old community, mostly ethnic Turkish descendants of Ottoman rule.
"Bulgarian society is traditionally known for its tolerance, mutual acceptance and respect between different ethnic groups and religions," President Rosen Plevneliev said in a statement. "Such an act is unacceptable in a democratic state."
Dogan, 58, who has lead the party for almost a quarter of a century, returned to the party conference a few hours after the attack and was greeted with standing ovation from delegates.
In 1996, former Prime Minister Andrei Lukanov was found shot dead near his home in Sofia, but attacks on politicians are rare in Bulgaria.