Health officials in northeastern Spain say 37 protesters have been injured during ongoing clashes with police at Barcelona's airport. Tempers flared in Spain's Catalonia region after the country's Supreme Court found 12 separatist leaders guilty of illegally promoting Catalan independence. Nine received prison sentences.

Regional police say they arrested two protesters — one at Josep Tarradellas Barcelona-El Prat Airport and another in the town of Mataro — for allegedly attacking officers.

Protesters threw empty fire extinguishers and other objects at the police. The police force confirmed its officers used foam bullets and batons to drive back enormous crowds at the airport.

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Regional emergency service SEM said 53 people were treated for injuries at the airport. Spain's airport operator, AENA, said at least 108 flights were canceled.

Police also clashed with angry crowds late Monday night in downtown Barcelona. They used batons and sounds similar to the firing projectiles were heard.

Police clash with protesters during a demonstration at El Prat airport, on the outskirts of Barcelona, Spain, on Monday, October 14, 2019. Spain's Supreme Court on Monday sentenced 12 prominent former Catalan politicians and activists to lengthy prison terms for their roles in a 2017 bid to gain Catalonia's independence, sparking protests across the region. Bernat Armangue / AP

Nine of the 12 Catalan politicians and activists were found guilty of sedition and given prison sentences of nine to 13 years. Four of them were additionally convicted of misuse of public funds.

The other three were fined for disobedience. The court barred all of them from holding public office.

All 12 were acquitted on the more serious charge of rebellion, which implied the use of violence, brought by state prosecutors and lawyers for the far-right Spanish party Vox. Vox leader Santaigo Abascal criticized the verdict as too light.

Spain's caretaker prime minister, Pedro Sánchez, said the outcome of the four-month trial proved the 2017 secession attempt had become "a shipwreck." Sánchez urged people to "set aside extremist positions" and "embark on a new phase" for Catalonia.

He said he hoped the prison sentences would mark a turning point in the long standoff between national authorities and separatist lawmakers in Barcelona, the Catalonia region's capital.

The Catalan separatist movement is going through its most difficult period in years. With a general election scheduled for November 10, its most charismatic leaders are behind bars or abroad after fleeing to avoid prosecution.

Catalan regional president Quim Torra described the court's verdict as "an act of vengeance." He said it "will not stop us from acting on our determination to build an independent state."