Some of the wounded tried to crawl away to escape the gunfire. Others bled to death on prayer mats as people tried to drag them to safety.

But the snipers and officers kept pulling their triggers, firing bullet after bullet into men and young boys at a worship area where Friday Prayer had been underway.

The horrific scene unfolded on Sept. 30 in Zahedan, a city in southeastern Iran that is home to the ethnic Baluch minority, after a small group of worshipers emerged from the Great Mosalla prayer complex to confront security forces posted at a police station across the street.

The protesters chanted antigovernment slogans and threw rocks at the officers, prompting the security forces to fire indiscriminately into the crowd, according to witnesses. As the demonstrators scattered, the gunshots stalked their retreat back toward the complex, where thousands were still praying.

“It was a massacre I had only seen in movies,” said Jamshid, 28, a worshiper, who was reached by phone and identified himself only by his first name to avoid reprisals. “They started shooting as people still had their heads bowed in prayer.” Young men threw themselves in front of children and older people to shield them from the bullets, Jamshid said. “People had nowhere to go.”

The massacre, called “Bloody Friday” by residents, represents the most lethal government action since a crackdown began against nationwide demonstrations a month ago. Sixty-six to 96 people were killed over the course of the next several hours, according to local and international human rights groups, including Amnesty International.

Videos obtained and analyzed by The New York Times show in detail an unbridled response by the security forces as the chaotic and bloody scene unfolded. In one video, men who appear to be snipers in plain clothes are seen on the police station’s roof firing into the street.

The unrest in the ethnic Baluch region also poses yet another serious challenge for the clerics in Tehran, who have been scrambling to contain the most serious antigovernment protests seen in years.

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The nationwide protests started in September after a young woman, Mahsa Amini, died in police custody after being arrested on an accusation of violating the government’s law on head scarves. But the demonstrations expanded to include broader calls for an end to rule by the Islamic Republic.

Anger in Zahedan boiled over after accusations surfaced that a Baluch teenager had been raped by a police officer in another city, fueling long-simmering discontent among the Baluch minority, predominantly Sunni Muslims, over the rule of the Shiite authorities in Tehran.

Zahedan is the capital of Sistan-Baluchestan, an arid province in the southeastern corner of the country and one of the least developed and most unstable parts of Iran.

Only now, two weeks after the crackdown — which has been largely concealed from Iranians by an internet blackout in the country — have details corroborating the scope of the killings in Zahedan started to emerge.

The Times spoke with 10 residents from Zahedan, including witnesses and activists; family members of the victims; and a medic who helped treat more than 150 people for wounds. All spoke on the condition of anonymity, for fear of retribution from the government. They echoed the accusation that security forces fired indiscriminately on unarmed protesters and civilians with bullets and tear gas. Helicopters were also deployed, according to witnesses.

Dozens of videos obtained, reviewed and verified by The Times support key parts of the narrative put forward by witnesses and activists.

The Islamic Revolutionary Guards Corps, an elite branch of the armed forces, has confirmed that its forces were present in Zahedan, and that six of its members were killed that day, including its regional intelligence chief, Col. Ali Mousavi, and officers from the feared Basij militia. They have denied firing on civilians.