NEW DELHI -- Five female activists working for an organization backed by a Christian missionary group were gang-raped at gunpoint in the eastern Indian state of Jharkhand this week, police said on Friday. The women were accompanied by four men and two nuns as they performed a street play to raise awareness of human trafficking in the Khunti district on Tuesday when at least six armed men attacked them.

They attackers beat the male members of the team and forced the five women into a car, took them to a nearby forest and raped them for three hours before releasing them, police officials have told CBS News.

"We have taken the statement of the victims," Homkar Amol Venukant, Deputy Inspector General of Police in Ranchi, the state capital of Jarkhand, told CBS News on Friday. The victims told officers that the attackers "filmed the act on their mobile phones," and threatened to publish the videos on the internet if the crime was reported.

The two nuns, who were part of the activists' team working to raise awareness of human trafficking, were not hurt, police told CBS News.

The attackers were reportedly agitated over the activists' entering the village without their permission. An anti-establishment self-rule movement, Pathalgadi, is popular in several tribal villages in the Indian state. Members don't recognize the authority of the local or national governments in their villages and have banned the entry of outsiders without permission.

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Police had not made any arrests in the case as of Friday.

"We have detained some suspects and are questioning them," Venukant told CBS News. It was not yet clear whether the people in custody were members of the local Pathalgadi. "This is a very sensitive case, we won't be able to share their identities at this stage," he said.

"The investigation is on. We will look at all angles to ascertain who is behind this heinous crime," Superintendent of Police, Ashwini Kumar Sinha, told CBS News.

The victims worked for an NGO called Asha Kiran, which is supported by a local Christian missionary group. Like several other NGOs, Asha Kiran is active in Jharkhand, which is considered to be the capital of human trafficking in India. Hundreds of children and adults are trafficked in India for commercial sexual exploitation and forced labour, most of them from the region.

India has a distressing record of sexual violence against women. About 40,000 rape cases were reported in 2016, according to government data. Last month, two teen girls were set on fire after being raped in Jharkhand.

There has been renewed outrage amid a rash of new high-profile sexual assault cases in India, and women's safety is gaining resonance as a political issue ahead of general elections next year.