Iran's security forces opened fire Thursday on mourners at a cemetery in Lorestan province to mark the 40th-day memorial for a young protester, Nika Shakarami.

The 16-year-old Nika Shakarami’s body was found in suspicious circumstances ten days after she left home to take part in a protest rally against compulsory hijab on September 20.

The last time she spoke to anyone, she was on the run from security forces chasing her on motorbikes. Authorities claimed that she was thrown off a roof or jumped to her death after taking part in the protests.

The teen’s aunt, Atash Shakarami, announced Wednesday in an Instagram post that the family would gather at the cemetery where she is buried to mark her 40th-day memorial. A huge crowd of people gathered Thursday at the cemetery in Veisyan village near Khorramabad where she was buried to commemorate her on day 40th of her death, which is a long-held tradition in Iran

So far around 250 have been killed by security forces, nearly a hundred of whom were killed in one day in Zahedan, Sistan and Baluchestan province when security forces opened fire on a crowd returning from Friday prayers on September 30. In the coming days there will be several such ceremonies every single day in various parts of the country for other victims.

As seen in videos posted on social media, security forces used tear gas and shot at participants in the ceremony in Veisyan.

Videos on social media show the mourners holding photos of Nika and chanting “Khamenei will be overthrown in this bloody year,” “We are all Nika, Fight us and we will fight back,” “Death to the Dictator,” “Death to Khamenei,” and “They took Nika away and brought her body back to us.” Videos also show people throwing stones at the security forces and singing a famous Luri folk song with the chorus “It's Time for War.”

This was the second 40th day memorial for the victims of government violence in protests triggered by Mahsa Amini’s death in police custody on September 16 . Huge crowds marked Mahsa’s own 40th-day memorial in her hometown of Saqqez and many other cities on Wednesday.

​Nika’s mother was not informed of her death for ten days. Authorities claimed Nika’s body was found in a courtyard at the back of a building on the morning of September 21 but had not been identified. They initially claimed she had been pushed to death from the roof and it “had nothing to do with the protests.” A report by state media later quoted a Tehran prosecutor as saying that Nika had committed suicide.

Nika’s aunt, Atash Shakarami, and her uncle were arrested by security forces for publicly speaking about the suspicious manner of Nika’s disappearance and death.Both were forced to appear on the state television to corroborate the official account of the teen’s death.

On Thursday, CNN published an exclusive investigation into Nika’s death. CNN said it received several videos and had eyewitness accounts that suggested Nika was chased and arrested by security forces on the night she disappeared. The video showed Nika ducking behind a vehicle shouting to the driver not to move to shield herself from security forces chasing her.