Catalonia's independence referendum campaign is officially underway, brushing aside Madrid’s firm pledge to prevent the October 1 scheduled vote from taking place through an official judicial suspension coupled with probes against regional mayors.

Thousands of Catalan independence supporters flooded a concert arena in the port town of Tarragona to set in motion a two week ‘Yes’ campaign that was initiated Thursday evening by the regional president, Carles Puigdemont.

“Somebody thinks that we won’t vote on Oct. 1? What kind of people do they think we Catalans are?” Puigdemont asked the crowd at Tarraco Arena Plaza. “In Catalonia, we are democrats.”

“Voting!”, “We are not afraid!” and “Where are the ballots?” chanted the crowd of roughly 7,500 pro-independence activists.

📸La Tarraco Arena plena a vessar! Tot a punt per començar la campanya pel Sí al #referèndum📩 a Tarragona #HolaRepúblicapic.twitter.com/6hmvNkZgXw — Esquerra Republicana (@Esquerra_ERC) September 14, 2017

“What do you think will happen on October 1? Of course, we will vote!" declared the president.

Madrid, however, insists the referendum is illegal. Spain's Constitutional Court has suspended the vote pending a formal decision by its judges. Authorities have been given orders to stop the ballot, and anyone helping to organize the referendum may be found legally liable.

READ MORE: Spain's state prosecutor orders probe into 700+ Catalan mayors for cooperating with referendum

On Wednesday, the Office of the Prosecutor summoned 712 regional mayors as part of efforts to investigate collaborators with the planned vote. Catalonia’s pro-separatist government had asked regional leaders to arrange facilities for polling stations.

Ple a vessar la Tarraco Arena! Comença el primer acte de campanya! Pots seguir-lo en directe aquí 👉🏼 https://t.co/OUPgN9aGfn#HolaRepúblicapic.twitter.com/ynNXvEsAHf — Junts pel Sí (@JuntsPelSi) September 14, 2017

Puigdemont denounced the central government’s actions and said in a future Catalan state, “no polls or ballots will be suspended, no mayors will be threatened, no media will be intimidated.”

Les cues ara mateix per entrar a l'acte d'inici de la campanya pel SÍ a #Tarragona. pic.twitter.com/3CH8QIebXo — Albert Mercadé (@albertmercade) September 14, 2017

The campaign's opening ceremony, which lasted two hours, was celebrated with much enthusiasm and optimism, despite Madrid's direct warning that staging a rally in the Tarraco Arena would constitute a crime.

READ MORE: 1mn Catalans mark national day with massive pro-independence march in Barcelona (PHOTOS, VIDEOS)

In spite of the legal threat, police allowed the rally to proceed and organizers managed to ferry in thousands of people from across Catalonia to Taragonna on 40 chartered buses.

La CUP inicia arreu del territori la campanya #prenpartit per demanar el Sí al #referèndumCAT. Ja ha arribat el #mambo! pic.twitter.com/vr7AAOhqRf — CUP #referèndumCAT (@cupnacional) September 14, 2017

Three huge banners graced the massive arena: 'Hello Europe', 'Hello Republic' and 'Hello New Country.'

Before Puigdemont took to the stage, Catalonia's vice-president pointed out that the mobilization of the ‘No’ camp remains “very important,” as there must be a valid opposition to validate the referendum results.

La policia identifica la primera tinent d'alcalde de Cerdanyola @VilaElvi en l'encartellada d'inici campanya pel Sípic.twitter.com/oqJXacOR8f — Llibertat.cat (@Llibertatcat) September 14, 2017

Oriol Junqueras told the crowd in Tarragona, about 100 kilometers (62 miles) south of Barcelona, that the move was all “about democracy,” as he called on people to be “defenders of the right to vote,” in order to create a republic that will be “free, fair and dignified.”

Somriures d complicitat d campanya xl SÍ d compromís i il.lusió, d futur i llibertat! La gent d'@Esquerra_sbd en marxa! #ASabadellVotarempic.twitter.com/77lUuW9jLQ — Juli Fernàndez (@julifernandez) September 14, 2017

“We have learned to take up the challenges in a massive and collective way, filling squares, towns and cities, and also ballot boxes. This is your strength,” said Junqueras.

“All that remains to be done depends on you. You must go out to vote massively on October 1. It is in your hands.”