The Islamic State is the “primary focus” of investigators after suicide bombings killed nearly 100 people at a rally here in the capital during the weekend, Turkey’s prime minister said Monday. But even as authorities vowed to identify the perpetrators, survivors of the bloodshed directed their anger at the government.

Labor unions, other workers and universities throughout the country went on strike and led protests against the government on Monday, pointing to a nation dangerously polarized by unrest and violent spillover from Syria’s civil war.

President Recep Tayyip Erdogan “can still rule the country if he wants to. But he divided us. After the bombings, one part of the country is not sorry that this happened,” said Veli Sacilik, a member of a civil servants union who witnessed the attack.

Erdogan and his Justice and Development Party (AKP) have governed Turkey since 2002, but the party lost its ruling majority for the first time in elections in June. The upset set off months of tense negotiations over a coalition government that ultimately failed. In the meantime, Turkey’s cease-fire with the militant Kurdistan Workers’ Party, which has waged a decades-long struggle for the rights of ethnic Kurds in Turkey, ended as both sides resumed attacks.

Erdogan had called for snap elections scheduled for Nov. 1, and opponents accuse the president of sabotaging the country’s politics to regain his party’s majority in the elections. Saturday’s demonstration, which mobilized activists from across the country, was supposed to serve as a nationwide call for peace.

Instead, at least 97 people were killed when two blasts ripped through the crowd of demonstrators in central Ankara on Saturday morning. The bombs exploded just seconds and yards apart and were detonated by two suicide bombers, officials said. It was the worst terrorist attack in the country’s history.

“If you consider the way the attack happened and the general trend of it, we have identified the Islamic State as the primary focus,” Prime Minister Ahmet Davutoglu said on Turkey’s NTV television, the Reuters news agency reported.

Turkey is a strong backer of rebels seeking to topple Syrian President Bashar al-Assad, but the four-year-old conflict has allowed the Islamic State militants to seize territory there and in Iraq — and now possibly mount attacks in major Turkish cities.

At the Ankara headquarters of Halkevleri, a rights group, the union leaders who organized the rally said it is possible that Islamic State bombers carried out the attack. But they also said that the government’s support for Sunni extremists in Syria emboldened the jihadists. The operation was a well-planned assault aimed at maximizing casualties, the activists said.

“Nothing can happen in Ankara without the knowledge of intelligence or the police,” said Samut Karabulut, Halkevleri’s director in Ankara. At the office, the unionists printed a three-page list of 130 victims they say were killed in the bombing. The list included the victims’ full names, birthplaces and the hospitals they were taken to by paramedics on Saturday. Karabulut and other activists accuse authorities of deliberately playing down the toll, but officials say the Health Ministry won’t announce the deaths until they have been verified through a government procedure.

The activists’ claim that there are 130 victims is “based only on anecdotes. The government has a verification process that includes notifying the families before a statement is issued,” said a senior Turkish official, who spoke on the condition of anonymity to speak freely about an ongoing terrorism investigation.

“It doesn’t help to have mainstream political parties blaming the government for the attacks without any evidence,” the official said. “It’s like saying the
Bush administration perpetrated 9/11.”

Witnesses of Saturday’s bombings said that police attacked demonstrators and volunteer responders in the wake of the blasts. Police fired tear gas at bystanders rushing to help.

Yuksel, a demonstrator from the Turkish city of Kars, said police pulled him away from a dying woman he had tried to help. Shrapnel had shredded the right side of her body, and blood was pouring from her ears.

“She grabbed my pant leg as I walked by and said, ‘Help me,’ ” Yuksel said. He did not want to give his full name for fear of arrest. “The police came and said: ‘Leave her! They are terrorists! They don’t deserve to be helped!’ ”

Yuksel said he shouted back: “You call yourselves Muslims? Then where is your humanity?”

Brian Murphy in Washington contributed to this report.