Hundreds of protesters stormed the Armenian parliament and later attacked the speaker of the house after a ceasefire agreement was signed between Armenia, Russia and Azerbaijan.
The peace deal was signed after Azerbaijan made several key gains in the fight for control over Nagorno-Karabakh, a territory technically in Azerbaijan but controlled by ethnic Armenians.
The deal will end six weeks of fighting that has devastated the region. By a conservative count, 1,400 people, both civilian and military, have died since the fighting began.
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However, Russia estimated the number was closer to 5,000.
The agreement will also result in the surrender of part of Nagorno-Karabakh to Azerbaijan and the deployment of 1,960 Russian military personnel and 90 armored personnel carriers to the region as peacekeepers.
Russia's President Vladimir Putin also called for a return of internally displaced people to their original homes.
On October 7, authorities in Nagorno-Karabakh put that number at 140,000.
The Russian troops will be placed both along the border of Nagorno-Karabakh and Azerbaijan and between the region and Armenia.
Russian peacekeepers deployed to Nagorno-Karabakh. /Reuters/ Russian Defence Ministry/
While the deal was celebrated in Azerbaijan, it has been heavily criticised in Armenia for its territorial concessions, resulting in hundreds of protesters storming the parliament building hours after the agreement was announced.
Protesters were looking for Armenia's Prime Minister Nikol Pashinyan, who was not in the building at the time.
In his absence, they chanted "resign!" or "out!", and ripped his nameplate off his office door.
While Armenian police officers were present at the time, the AFP news agency reported that they did little to stop the protesters.
Ararat Mirzoyan, the speaker of the Armenian parliament, was also reportedly attacked by a group of people who pulled him out of his official car.
Police outside Armenia's parliament the day after protests. /Reuters
He is reported to be in a critical condition and Pashinyan has said several of Mirzoyan's assailants have been arrested.
In a Facebook Live, Pashinyan justified signing the controversial deal, stating: "The army said that it was necessary to stop, because there are problems that have no prospects for solutions, our resources are exhausted."
He then called for the "citizens of the Republic of Armenia to remain calm and to unite."
Artyom Tonoyan, an Armenian analyst, said on twitter after the deal was signed that: "I don't see how Pashinyan survives this."
He later added that the protesters "want [Pashinyan's] head on a pike."
Video editor: Natália Luz.