People protested in front of government buildings in a north-west Iranian city after one of the biggest nights yet of demonstrations.
The human rights group Hengaw said police shot dead a male protester in Mahabad and another in Sanandaj. The BBC has not verified this.
Widespread unrest has rocked Iran since Kurdish Iranian woman Mahsa Amini died in police custody 40 days ago.
A cemetery near Kharamabad was also a flashpoint for Thursday's protests.
Demonstrators gathered at the cemetery to mourn another young woman, Nika Shakarami, who disappeared soon after Amini's death and has become another symbol of the protest movement.
Videos from Kharamabad showed protesters chanting anti-state slogans including "down with the dictator", a reference to Iran's supreme leader, Ayatollah Khamenei.
Overnight, tens of thousands of people took to the streets in major cities, as well as other places where demonstrations had subsided recently.
It is the most serious challenge to the Islamic republic since its inception.
Norway-based Iran Human Rights said at least 234 protesters, including 29 children, have been killed by security forces in crackdowns so far. Iran's leaders have portrayed the unrest as "riots" fomented by foreigners.
Footage posted on social media and verified by the BBC show widespread protests on Wednesday night.
Other cities, such as Andimeshk and Borujerd in the west, and Lahijan, near the Caspian Sea in the north, also saw a resurgence of protests.
The upsurge came after a day on which police were reported to have opened fire on protesters in Saqqez, home city of Mahsa Amini, who died in custody after being arrested for allegedly wearing her hijab "improperly".
Thousands had gathered to mark 40 days since her death. A rights group and witnesses said officers fired live rounds and tear gas at the crowds in the city. Numbers of casualties are not known.
In the city of Arak, drivers spot a fire on top of a mountain burning in the shape of the name Mahsa in Persian tonight, as Iranians mark 40 days since the death of #MahsaAmini in morality police custody.#مهسا_امینیpic.twitter.com/9AGKIbW7vJ
— Shayan Sardarizadeh (@Shayan86) October 26, 2022
"The society is very angry. We had enough of them [Iranian leadership]," a 27-year-old female protester in Karaj, close to Tehran, told BBC Persian.
"I want to have the right to say no to these people. I'm tired of being a second-class citizen. Because I am a woman. Men are tired of the intimidations by the regime. This is the first time in the history of our country that we stand together for a goal which is woman, life and freedom."
Protests swept across Iran after Amini, 22, died on 16 September.
She had been detained three days earlier by the morality police in 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.
The BBC and other independent media are banned from reporting from inside Iran, making state media and other reports hard to verify. Authorities have also heavily disrupted the internet, hampering the ability of protesters to post on social media.
- BBC