Iranian police are reported to have fired on protesters in Saqqez, home city of Mahsa Amini who died in custody after being arrested for allegedly wearing her hijab "improperly".
Thousands gathered near the grave of the Kurdish woman and clashed with security, 40 days since her death.
A rights group and witnesses said officers fired live rounds and tear gas at the crowds in the city.
Protests swept across Iran after Ms Amini, 22, died on 16 September.
She had been detained three days earlier by the morality police in the capital, Tehran, and fell into a coma after collapsing at a detention centre.
There were reports that officers beat her with a baton and banged her head against a vehicle, but police denied that she was mistreated and said she suffered a heart attack.
On Wednesday, security forces were deployed in Saqqez and other parts of Kurdistan province, in anticipation of fresh demonstrations on the 40th day of mourning for Ms Amini - a culturally significant occasion for Iranians.
Videos showed thousands of mourners walking along a road, through a field and across a river to bypass roadblocks and reach the graveyard where Ms Amini is buried.
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It was not clear whether members of Ms Amini's family were present.
A source close to the family told the BBC's Jiyar Gol that intelligence agents put pressure on her father to say that they were not holding a ceremony.
Kurdish human rights group Hengaw, which is based in Norway, later tweeted that mourners had marched towards the provincial government's office in Saqqez and that security forces had opened fire on people in Zindan square.
Reuters news agency quoted an unnamed eyewitness as saying: "The riot police shot mourners who gathered at the cemetery... Dozens have been arrested."
The semi-official Isna news agency reported that "a limited number of those present at Mahsa Amini's memorial clashed with police forces on the outskirts of Saqqez and were dispersed".
Hengaw also reported demonstrations in several cities in Kurdistan. It said police had used live fire in several places, iincluding in Marivan.
The first protests took place after Ms Amini's funeral in Saqqez, with women ripping off their headscarves in solidarity.
The protests evolved into one of the most serious challenges to the Islamic Republic since the 1979 Iranian revolution.
Women have been at the forefront, waving their headscarves in the air, setting them on fire and even cutting their hair in public.
Another Norway-based organisation, Iran Human Rights, says at least 234 protesters, including 29 children, have been killed by security forces in a crackdown on what Iran's leaders have portrayed as "riots" fomented by foreigners.
Opposition activists said protests marking the 40th day of mourning for Ms Amini were also held in other parts of the country, including Tehran.
Video appeared to show that security forces fired tear gas inside a girls' school in the capital in response to a protest by students.
One young female protester inside Iran told BBC World News: "You cannot imagine how tough it is to go to streets knowing that they are ready to shoot. But we are not afraid.
"It's not about me. It's about the next generation. We want to have a normal life."
She added: "I don't know when our protests will come to an end, but today Iranian society is more awake than ever and we are ready for big changes."