More than 50,000 people took part in the rally in Minsk, according to the Viasna human rights center. Demonstrators carried banners mocking President Alexander Lukashenko, who has run the country for 26 years, and chanted “Go away!”

Mass protests have rocked Belarus since the Aug. 9 presidential election that handed Lukashenko a victory with 80% of the vote. His main challenger, Sviatlana Tsikhanouskaya, got 10%. She and her supporters refused to recognize the results, saying the outcome of the vote was manipulated.

Authorities tried to quell the unrest with mass detentions and police dispersing crowds with truncheons, stun grenades and water cannons. On Monday, the country’s Interior Ministry threatened to use firearms against the protesters “if need be,” saying that the rallies “have become organized and extremely radical.” However, the protests have continued despite the crackdown.

“This is the first march since the authorities threatened to use firearms. But even that didn’t stop the protest, which transforms into different forms, but doesn’t die down,” Viasna leader Ales Bialiatski said.

Tsikhanouskaya, who is currently in exile in Lithuania after leaving the country in fear for her safety, threatened on Tuesday to call a nationwide strike unless Lukashenko announces his resignation, releases political prisoners and stops the crackdown on protesters.

“If our demands aren’t fulfilled by Oct. 25, the entire country will peacefully take to the streets,” Tsikhanouskaya said in a statement. “On Oct. 26, a national strike of all enterprises will begin, all roads will be blocked, sales in state-owned stores will collapse.”

Protestors on Sunday marched down one of Minsk’s main avenues, where plants and factories are located, and chanted “Strike!” and “The workers are with the people.”

The city center was blocked off by water cannons and armored vehicles, and dozens of military trucks were seen driving around the streets. Several subway stations were closed, and mobile internet wasn’t working in the area of the march.

“Lukashenko understands that if there hadn’t been all these artificial obstacles, the entire Minsk would have come out (to rally),” said Valery Karbalevich, an independent political analyst in Minsk.

“Despite the threats of using firearms and intimidation by the KGB (Belarus’ State Security Committee), people take to the streets — the protests are not winding down, and it shows that the political crisis in Belarus is in full swing,” Karbalevich said.

In a statement Sunday, Tsikhanouskaya encouraged Belarusians to continue peaceful protests.

“Let’s continue to express our demands peacefully and persistently — it is yielding results,” she said, adding that authorities have released Ilya Salei, the lawyer of Tsikhanouskaya’s top associate, Maria Kolesnikova, from detention.

Kolesnikova was jailed last month on charges of undermining state security that could bring a five-year prison term if she’s convicted. Salei was detained in September as well in relation to the same charge.

Aside from Minsk, the protests on Sunday took place in several big cities, including Brest, Grodno, Gomel and Vitebsk. Scores of demonstrators have been detained across the country: the list of detained protesters released by the Viasna center on Sunday evening had over 150 names on it.