Security forces in Belarus Sunday moved to violently crush protests that broke out against the results of an election that showed an overwhelming victory for the country’s authoritarian leader, Alexander Lukashenko.

Hundreds of heavily armored riot police and interior ministry troops used water cannons, stun grenades and rubber bullets to disperse throngs of demonstrators gathered in the capital of Minsk shortly after exit polls were announced on Sunday evening.

Videos posted to social media by journalists showed lines of police, carrying metal shields, advancing on peaceful crowds in the city center and lobbing stun grenades.

Demonstrators were pushed back by armored cars and water canons, as police sealed off some streets. Dozens of people were reported arrested. Photos from the scene showed bloodied protesters, and in one video a police truck appeared to drive over a demonstrator.

The protests began shortly after a state exit poll showed Lukashenko winning the national election with 79.7% of the vote, with just 6.8% going to his main opposition rival, Svetlana Tikhanovskaya, who has been leading a groundswell movement to remove him.

Sunday’s vote was preceded by weeks of opposition rallies that have been the largest political protests in Belarus since the fall of the Soviet Union, and were seen as an unprecedented challenge to Lukashenko who has already been in power for 26 years and is often nicknamed “Europe’s Last Dictator”.

Police confronted protesters in a number of cities across Belarus and there were reports of clashes in some, including Gomel and Vitebsk. In some smaller cities, police were reported not to have engaged protesters.

On Sunday, internet access in Belarus was partly shut down for most of the day, and by evening many social media platforms and messaging apps, including WhatsApp and Viber, were not working. The websites of some of Belarus’ largest independent media outlets were also unreachable. Belarus’ government had declined to give journalists from most foreign news organizations permission to work in the country ahead of the vote.

Tikhanovskaya, whom the opposition has unified behind, called on police to stop using violence against protesters.

“I’d like to ask the police and troops to remember that they are part of the people. I ask my voters to prevent provocations,” she said in an appeal through the news outlet tut.by. “I know that Belarusians tomorrow will already wake up in a new country, and I hope that tomorrow there will only be good news. Please stop the violence.”

A former teacher until a few months ago, Tikhanovskaya was a stay-at-home mother but became a candidate after her husband, a popular blogger, was jailed and barred from running. She joined with two other women, Maria Kolesnikova and Veronika Tsepkalo, to focus an unprecedented wave of dissatisfaction against Lukashenko.

Tikhanovskaya was moved to an undisclosed location in Belarus on the eve of the vote, amid fears police were moving to arrest her. She emerged to vote at a polling station on Sunday but went back into hiding afterward.

Her ally Tsepkalo left Belarus on Sunday for Moscow, where her husband, Valery Tsepkalo, another opposition leader barred from running, is already in self-exile with their children.

Tikhanovskaya’s supporters denounced the landslide result for Lukashenko as fabricated, and said their own exit polls showed a majority of Belarusians had voted for Tikhanovskaya.

On Sunday, her campaign claimed that she had won a large majority at polling stations in Minsk.

None of the previous five elections under Lukashenko have been deemed free and fair by international observers, and few observers had expected the government would announce anything other than a substantial win for the former collective farm manager this time around.

Opposition observers pointed to the record number of early votes — an unprecedented 40% according to Belarus’ central elections commission — as a sign of widespread ballot stuffing.

Before the result was announced, Lukashenko said he did not expect foreign countries to recognize it. Ahead of the election he had threatened to use force against demonstrators, denouncing the opposition as backed by foreign powers and accusing them of seeking to foment a revolution.

At a polling station earlier in the day where he cast his vote, Lukashenko dismissed Tikhanovskaya and the rest of the opposition as “not worth enough to carry out any repression against them,” he said.

Ahead of the vote, European countries including France, Germany and Poland called on Belarus’ government to respect Belarusians’ right to free elections.