Police fired rubber bullets, wrestled protesters, smashed doorways and carted off ballot boxes in several parts of Barcelona on Sunday, as long lines of people voted in an independence referendum that could radically reshape politics across a divided region.

The outbreaks of police violence at a handful of polling locations served to heighten tensions in the Catalan capital, potentially boosting turnout for a vote that could have significant consequences for the autonomous region’s future, and that of Mariano Rajoy’s Spanish government.

After polls closed Rajoy made a televised address reiterating that voters had been tricked by Catalonia’s political leaders, and that the national police had simply responded in accordance with their orders.

Ricard Gene, 56, a commercial lawyer who had volunteered to help at a polling station inside the Miquel Tarradell secondary school in Barcelona’s Ciutat Vella – or Old City – said he was shocked by the images of violent police tactics that played out across his city, as ordinary citizens sought to vote in a referendum that Spain’s constitutional court had already declared illegal.

“We thought it would be hard, but never this hard,” he told CNBC as he handed out ballot papers to Catalans who trickled in to the secondary school’s entrance hall.

He had walked just fifteen minutes that morning from home to his assigned voting location, where the school foyer was filled with tables, ballot boxes and fellow volunteers. By mid-afternoon his team had ushered “hundreds, maybe thousands” of voters through the process.

The ballot papers had been printed in secret and delivered just after 8 a.m. local time, while volunteers interlocked arms to prevent national police from capturing them.

Voting begun at 9.10 a.m. on Sunday, Gene said proudly, but since that time the computer system used to count votes and check identities had crashed several times. A surging crowd 10 feet deep greeted each group of exiting voters with applause, stepping forward from the front door to allow them to pass, then immediately standing back to re-block the entrance.

A handful of police officers watched from a distance, as John Lennon’s “Imagine” played through loudspeakers and organizers led chants and repeated clapping.

The Catalan government had said 2,300 schools and town halls were designated as polling stations, and ultimately the Spanish authorities closed just a fraction of those. Catalan lawmakers, hundreds of local bureaucrats and roughly two thirds of the 948 mayors in the region had offered up their government buildings to host the poll, and as a consequence many had been charged with sedition and rebellion alongside senior Catalan government officials, who also faced heavy fines.

The question asked of voters: “Do you want Catalonia to become an independent state in the form of a republic?,” required just a simple yes or no response. But the emotions of many standing in line on polling day were complicated.

“The behavior of the police makes people who don’t want independence, want independence,” said a hotel worker called Alice, whose dog stood beside her as she waited for the chance to vote against Catalan secession.

But hers was a rare voice on the streets of Barcelona on Sunday, with the Catalan government claiming that around 90 percent of voters had opted for independence. Previous opinion poll numbers suggest that support for independence peaked at 49 percent back in 2013, raising questions about turnout. It may be several days until the final vote numbers are made public, and though critics have undermined the integrity of the referendum as well as its legality, the Catalonian Justice Minister Carlos Mundó asserted that Sunday’s results would be binding regardless of participation levels.

Catalonia’s cultural and linguistic differences are rooted in a centuries old history, but it was only in recent years that the region’s representatives began demanding the budgetary and fiscal independence that is currently enjoyed by the nearby Basque region of northern Spain. But Rajoy’s Partido Popular has repeatedly blocked negotiations since 2012. Stoked by increasingly vocal separatist politicians, Madrid’s intransigence prompted many Catalans to consider a vote for independence that would have attracted far fewer adherents as recently as a decade ago.

So what began as a financial disagreement between the two governments over taxation has – thanks to the increasingly heated rhetoric of leaders on both sides – transformed into a visceral, emotional argument over national identity. Spain’s long-time military dictator General Francisco Franco banned Catalan as a language, and crushed all separatist sentiment during his long period in power. Over the weekend Catalan critics of Rajoy’s center-right Madrid government frequently made comparisons to Franco’s fascist forces, as Spanish military police in riot gear prevented the Catalan President Carles Puigdemont from voting in his own district.

Puigdemont eventually cast his ballot in a small village to the north of Barcelona, called Cornella del Terri, after repeatedly criticizing the behavior of Spanish authorities and insisting that the referendum result would stand.

On Monday morning, as sanitation workers outside Barcelona’s Generalitat – the seat of the Catalan government – pulled down independence flags and scrubbed off the egg-shells thrown by anti-independence protesters the night before, there were few clear indications of what happens next. Puigdemont’s regional government – formed from a coalition of separatist parties that only passed a law to hold the referendum a month ago – had previously hinted it would not yet unilaterally declare independence. But the excessive zeal and force employed by Madrid-controlled police has almost certainly boosted the separatists’ cause. And as an embattled Rajoy meets with his political allies and opponents in the Spanish capital, he could decide to arrest yet more senior Catalan figures and suspend Catalonia’s autonomy, as permitted under Spain’s constitution. Both regional and national governments are led by minority parties in unstable coalitions; with decisions being made amidst this largely self-inflicted political maelstrom, that fact could make it hard for both sides to back down.