Islamabad, Pakistan – At least 25 people have been wounded after an attack by gunmen on members of the Pashtun Tahafuz Movement (Pashtun Protection Movement or PTM) rights group in northwestern Pakistan, security sources and rights activists say.

Gunmen said to belong to the Pakistan Taliban opened fire on the rights activists, led by PTM leader Ali Wazir at a gathering in the South Waziristan tribal district on Sunday.

Local media reported that at least three members of the movement were killed in the violence, but Al Jazeera was unable to independently verify that figure as communications to the area had been cut.

Video footage released by PTM showed people taking cover in a bazaar in the town of Wana, the capital of South Waziristan, as gunfire rocked the marketplace.

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“They started beating people and firing upon them,” said Mohsin Dawar, a senior PTM leader. “People threw stones back at them. There were a lot of casualties.”

Alam Zeb Mehsud, another PTM leader, who coordinated medical aid to the wounded, confirmed the violence to Al Jazeera, saying reports from those injured indicated “the death toll could be as high as seven”.

Paramilitary forces were deployed soon after the violence broke out, imposing a strict curfew in the area overnight.

At a press briefing on Monday, military spokesperson Major-General Asif Ghafoor told reporters it was a government-sponsored “peace committee” that had clashed with the PTM activists. He confirmed that paramilitary forces intervened to end the fighting and evacuated the wounded.

Residents told Al Jazeera that several members of the “peace committee” were former members of the Pakistan Taliban who had surrendered to security forces in recent months.

Strident criticism of Taliban, military

Since January, the PTM has been holding rallies across Pakistan demanding rights for the country’s roughly 30 million ethnic Pashtun citizens, who are mainly resident in the country’s northwest, where Pakistan has fought a bitter war against the Taliban and its allies since 2007.

Its leaders have stood against the Tehreek-e-Taliban Pakistan (TTP), with several of Wazir’s family members killed for their resistance against the armed group. PTM leaders Mehsud and Dawar confirmed that Wazir had recently received Taliban death threats for his involvement with PTM.

PTM has also alleged widespread rights abuses by the country’s military, in particular on the issues of extrajudicial killings and enforced disappearances of “terrorism” suspects.

According to a government commission on enforced disappearances, more than 4,900 people have been reported missing in Pakistan since 2011.

An Al Jazeera investigation in April documented 22 disappearances, including cases where those taken were held in a network of military-run internment centres without charge, tried by military courts, killed or released after allegedly being tortured.

The PTM’s strident and open criticism of Pakistan’s powerful military – which has ruled Pakistan for roughly half of its 70-year history – is rare in a country where critics of the so-called “establishment” face widespread censorship.

The core of PTM’s leadership, including Wazir and PTM chief Manzoor Pashteen, hails from South Waziristan, once the headquarters of the Tehreek-e-Taliban Pakistan (TTP), or Pakistan Taliban.

The Pakistani military launched a widespread military operation to retake the district in 2009, forcing TTP fighters into neighbouring North Waziristan. It has undertaken a series of military operations since then to drive the TTP’s leadership out of the northwestern tribal districts and into, Pakistani security officials say, northeastern Afghanistan.

The military maintains tight control over the tribal districts, and particularly over South and North Waziristan, through a large deployment of troops and a network of security check posts which control all movement into, out of, and around the districts.

PTM chief Pashteen called for widespread protests on Monday after the attacks, saying the movement was determined to remain peaceful.

“The PTM has made constitutional demands. For five months, despite having many protests, we have not shut down a single road for a single minute … Our activists have been detained, they have been tortured, everything has been done to them, but they did not react,” he said in a video statement released shortly after the violence in Wana.

“We have raised our voices peacefully … The PTM, as human beings, are dealing with [those against it] on the basis of humanity. But they are determined to act like animals.”

Asad Hashim is Al Jazeera’s Digital Correspondent in Pakistan. He tweets @AsadHashim