(NewsNation) — Iranian authorities are denying reports that security forces killed 16-year-old protester Sarina Esmailzadeh. Iranian media is reporting the girl fell off a roof, but rights group Amnesty International says they reviewed photos and videos showing Esmailzadeh being “severely beaten in the head with batons.”

Esmailzadeh is one of about 52 people whom Amnesty International reports were killed during protests over the death of 22-year-old Mahsa Amini, who was in the custody of “morality police” when she died.

Iranian authorities claimed late last month that another teenage protester, 17-year-old Nika Shakarami, also died after falling off a roof. The girl’s mother Nasreen Shakarami rejected that explanation and says her daughter was killed by blows to the head as part of the crackdown on anti-hijab protests.

Jamil Jaffer, a George Mason University law professor, told NewsNation the security force’s response is likely to become more aggressive as protests continue.

“This is simply not acceptable, and the Iranian people know it,” Jaffer said.

Demonstrations began Sept. 17 at Amini’s burial site.

Since the election of hard-line President Ebrahim Raisi last year, morality patrols have grown more aggressive, with videos circulating of officers manhandling young women over their clothes or loose mandatory headscarves, known as hijabs.

An Associated Press tally of reports in state-run and state-linked media showed Friday there have been at least 1,900 arrests connected to the protests. Demonstrations have been reported in at least 50 cities, towns and villages.

The Associated Press and Reuters contributed to this story.