Large groups of people in Catalonia have gone on strike across the region in protest at the violent crackdown by Spain’s national security forces on the Catalan voters attending an independence referendum on the weekend.

The Tuesday general strike was called by more than 40 unions and associations in the region under the umbrella organization Table for Democracy in order to “vigorously condemn” the brutal police response to the voting process on Sunday.

The stoppage is expected to disrupt flights, train services and port operations in the autonomous region on Tuesday. Catalan public universities, the contemporary art museum and football clubs will also join the walkout.

More than 90 percent of Catalan voters said ‘Yes’ to separation from the mainland in a plebiscite banned by the central government.

The Sunday vote, however, turned ugly as Spanish riot police moved in on polling stations to stop people from casting their ballots. Security forces used batons and rubber bullets to disperse the crowds of voters.

More than 840 people were injured in the violent clashes between riot police and voters in one Spain’s worst crises in decades.

Madrid has pledged to prevent the wealthy northeastern region from breaking away from Spain and has dismissed Sunday’s poll as unconstitutional and a “farce.”

FC Barcelona backs strike

Meanwhile, FC Barcelona, one of the main symbols of the Catalan region, also said it will join the Tuesday strike. The football club has openly voiced support for the region’s right to hold the referendum.

While many players from Barcelona’s first team will leave to join their national squads ahead of the upcoming international fixtures, the remaining players and club staff will not attend the training center on Tuesday.

“FC Barcelona joins the country wide strike called for by the Table for Democracy and therefore the club will be closed tomorrow,” Barcelona tweeted on Monday. “None of the professional teams or the youth teams at FC Barcelona will train tomorrow at the Ciutat Esportiva.”

Espanyol and Girona, also based in Catalonia, released statements on Monday declaring their intentions to join the general strike as well.

In protest at the violent events on Sunday, Barcelona held their La Liga clash with Las Palmas behind closed doors, winning 3-0.

On Monday, there was an organized region-wide ‘standstill protest, with workers across Catalonia stopping work for 15 minutes at midday, including employees at Barcelona club offices.

In Barcelona, municipal police said about 15,000 people stopped traffic as they rallied, shouting “the streets will always be ours.

The Spanish police clampdown has also been met with international criticism.

The United Nations called on Spanish authorities on Monday to launch a complete and fair investigation into the violence invoked during Catalonia’s independence referendum.

UN High Commissioner for Human Rights Zeid Ra’ad al-Hussein said he was “very disturbed” by the clashes and urged Spanish authorities to run a thorough, independent and impartial investigation.

Catalan leader Carles Puigdemont has announced that results of the referendum will be sent to the Catalan parliament in the next few days to unilaterally declare independence.

“The citizens of Catalonia have won the right to an independent state in the form of a republic,” Puigdemont said in a televised address after the vote.

Puigdemont has called for international mediation to help solve the crisis.