Syrian police have broken up a large protest by Kurdish demonstrators in the town of Qameshli, residents said.
Kurdish residents want answers about Khaznawi's death
Tension has been rising since the burial of a prominent Kurdish cleric last week who locals believe was killed by members of the intelligence service.
Police opened fire in the air on Sunday to disperse crowds who threw stones and tried to attack them with sticks, witnesses are quoted as saying.
A policemen is reported to have died in the clash, but the cause is not clear.
Correspondents say it is not clear whether the policeman was inadvertently killed by friendly fire or by protesters.
There has been no word from the government on casualties.
Last year, five days of riots in Kurdish areas left 25 people dead and hundreds injured. They were sparked by a brawl at a football match in Qameshli between rival Arab and Kurdish fans.
Correspondents say Qameshli had been tense since the death of Sheikh Muhammad Mashuq al-Khaznawi, whose body was found in a mortuary in Deir al-Zour last week.
Sunday's protest was called by two banned Kurdish parties to demand an investigation into the murder of Sheikh Khaznawi.
The government says his murder was purely criminal and denies the sheikh had been arrested by any state security body.
In a further twist to the violence, Kurdish residents are quoted as saying that police stood by as looters from local Arab tribes pillaged at least 80 Kurdish shops in Qameshli during Sunday's confrontations.
Amnesty International has called for an investigation into the death of a Sheikh Khaznawi, alleging that he was tortured to death.
Syrian Kurds - who make up about 10% of the country's 17 million people - complain of discrimination and demand the right to speak their language.
Amnesty said the 48-year-old sheikh is at least the sixth Syrian Kurd to have died as a result of torture and ill-treatment in custody since March 2004.