A demonstrator in Tehran holds a picture of a victim of last week’s Ukrainian plane crash in Iran. Iran at first denied then admitted to having shot down a Ukrainian passenger jet by mistake January 8, killing all 176 people on board. (STR/Agence France-Presse/Getty Images)

Iranian police and security forces fired ammunition and tear gas to scatter demonstrators protesting the government’s initial denial that it had shot down a Ukrainian jet, online videos were said to show Monday.

Videos sent to the Center for Human Rights in Iran and later verified by the Associated Press show demonstrators in Tehran fleeing as a tear-gas canister lands among them. People cough while trying to escape the fumes., with one woman calling out in Farsi: “They fired tear gas at people! Azadi Square. Death to the dictator!” Another video shows a woman being carried away as those around her cry out that she has been shot in the leg.

International rights groups have called on Iran to let people protest peacefully as allowed by the country’s constitution.

Riot police in black uniforms and helmets gathered earlier Sunday in Vali-e Asr Square, at Tehran University and other landmarks. Revolutionary Guard members patrolled the city on motorbikes, and plainclothes security men were also out in force.

The crash of the Ukraine International Airlines jet Wednesday killed all 176 people onboard, mostly Iranians and Iranian Canadians. The Iranian government for three days suggested that the plane crashed because of a technical failure. On Saturday, after other nations found evidence that the Iranian military was to blame, authorities admitted that it accidentally shot down the plane the plane.

Iran downed the flight after firing ballistic missiles at two bases in Iraq housing U.S. forces earlier on Wednesday. The missile attack, which caused no deaths, was a response to the killing of General Qasem Soleimani, Iran’s top general, in a U.S. airstrike in Baghdad.

Iranians have expressed anger over the downing of the plane and the misleading explanations from senior officials in the wake of the tragedy. They are also mourning the dead, which included many young people who were studying abroad.

“Even talking about it makes my heart beat faster and makes me sad,” said Zahra Razeghi, a Tehran resident not taking part in demonstrations. “I feel ashamed when I think about their families.”

“The denial and covering up the truth over the past three days greatly added to the suffering and pain of the families, and me,” she added.

— Associated Press