Gunmen critically wounded the Turkish ambassador to Yugoslavia today in an ambush of the envoy's car. An Armenian nationalist group claimed responsibility.

One of the attackers was seriously wounded and apprehended by police. One passer-by was killed and two wounded in a hail of gunfire that came as Yugoslav agents chased the assailants through a park across from the federal parliament building. Yugoslav authorities searched for the second terrorist who escaped.

The ambassador, Galip Balkar, was reported in critical condition after emergency surgery in a Belgrade hospital for what doctors said were two bullet wounds--one in the head, the other through the right shoulder to the spine. His driver was slightly wounded.

The attack occurred at a major downtown intersection as the ambassador's black sedan stopped for a red light. The assailants opened fire with small firearms, according to a Yugoslav government statement, then attempted to run from the scene.

Two Yugoslav security agents in the area chased them and shots were exchanged, according to witnesses.

A group calling itself the Justice Commandos of the Armenian Genocide claimed responsibility for the action in messages to news agencies in several European capitals. Yugoslav officials identified the attackers simply as holders of Lebanese passports.

The messages said the shooting was intended to draw the world's attention to what the group called "the national problem of the Armenian people and the revolting injustice to which it continues to fall victim." Unnamed governments were accused in the messages of repressing Armenian guerrilla movements.

The commando group is a terrorist unit that is blamed for at least a dozen attacks on Turkish targets since 1975. Such violence, says the group, is aimed at directing attention to the fate of the world's 4 million Armenians and demands for a return to the ancient Armenian homeland, which lies in what is now eastern Turkey and part of the Soviet Union.

Armenian nationalists accuse the Turks of slaughtering 1.5 million of their countrymen in 1915 when the Turkish government, suspecting the Armenians of collaborating with the neighboring Russian enemy, drove many from their homes. Successive Turkish governments have disputed the numbers involved. Today, about 50,000 Armenians live in Turkey and Armenian refugees are scattered across the world.

The terrorist group is believed to be separate from another major Armenian guerrilla unit, the Armenian Secret Army for the Liberation of Armenia.