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Emrah Gurel, Associated Press
People hold images of victims as they protest Saturday's explosions in Ankara, Turkey, Tuesday, Oct. 13, 2015. Authorities in Istanbul banned a protest rally and march by the same trade union and civic society groups who lost friends and colleagues in Turkey's bloodiest terror attack. Dogan news agency video footage on Tuesday showed police pushing back dozens of demonstrators trying to reach the rally to commemorate the 97 victims of the twin suicide bombings. Some demonstrators were detained.

ANKARA, Turkey — Turkish authorities on Tuesday banned a protest rally and march by trade union and civic society activists who lost friends and colleagues in Turkey's bloodiest terror attack, but hundreds of people defiantly gathered for the protest.

The two suicide bombings on Saturday came amid political uncertainty in the country — just weeks before Turkey's Nov. 1 election which is in effect a re-run of an inconclusive June election. The bombings raised fears that the NATO country, a candidate for European Union membership, may be heading toward a period of instability.

The blasts have further polarized Turkey, as it grapples with more than 2 million refugees and tries to avoid being drawn into the chaos in neighboring Syria and Iraq.

Dogan news agency video footage on Tuesday showed police pushing back a group of demonstrators trying to reach the rally to commemorate the 97 victims of the two blasts.

Plain-clothed police pushed at least two demonstrators to the ground and detained them.

"Our brothers were killed! What are you doing?" a woman was heard shouting.

Riot police formed a line in front the entrance of a university preventing hundreds of other demonstrators from leaving to attend the march.

The Istanbul governor banned the protest citing "sensitivities at this time" and because the routes demonstrators planned to march along were heavily used by the public.

Several small protests — involving dozens to a few hundred people — have erupted across Turkey since Saturday with people expressing their grief and their grievances. Some protests have turned into anti-government demonstrations, with participants shouting slogans holding the government responsible and expressing dismay that no government official has taken responsibility and resigned.

Prime Minister Ahmet Davutoglu has said the Islamic State group was the main focus of the investigation. Authorities said Saturday's attacks bore similarities with a suicide bombing that killed 33 activists at a town near the border with Syria in July. No one has claimed responsibility for Saturday's explosions that also wounded hundreds.

The bombers likely infiltrated Turkey from a neighboring country, according to Deputy Prime Minister Numan Kurtulmus. He said several arrests were made in connection to the attacks but did not elaborate.

As with previous terror probes, authorities imposed "partial secrecy" on the investigation which even restricts defense lawyers' access to information. The government has also banned the publication of images of the aftermath of the attack.

In Ankara, some 200 students held a brief sit-in at Ankara University's faculty of political science to commemorate the victims. Police fired tear gas to disperse another group of some 400 people who tried to march in the city.

The youngest victim was 9-year-old Veysel Atilgan, who died in an explosion outside Ankara's main train station, along with his father. He was buried on Monday following an emotional ceremony at his school.

The city is on edge following the blasts and on Tuesday, police detonated a suspicious bag found near the station's VIP lounge, hours after Davutoglu visited the site to lay carnations in respect to the victims. The bag, however, contained food.