Barcelona - Moments after Spanish Prime Minister Mariano Rajoy announced that Spain would assume control of Catalonia's government, the streets of Catalonia's capital were once again filled with noise.

An estimated 450,000 people on Saturday gathered in Barcelona's centre to protest against Madrid's move to impose direct rule over them, a move regional officials described as a "coup".

Carrying the Estelada, the single-starred flag that symbolises an independent Catalonia, separatist supporters filled the city's streets and squares, while Spanish police helicopters buzzed overhead.

"We Catalans have no fear," protester Octavi Marti said, in response to Rajoy's decision to trigger Article 155 and dissolve the Catalan government.

"We will outlast them," the 39-year-old added.

'Young movement'

Catalonia voted in a disputed independence referendum on October 1 that met a heavy police crackdown from the Spanish national police and civil guard, a military force tasked with domestic law enforcement.

The Catalan government said 90 percent voted in favour of secession, but turnout was less than 50 percent.

Since then, protests have become an almost daily occurrence in Barcelona - and Saturday was no different.

Residents across the city of 1.6 million were banging pots and pans outside their windows to announce their displeasure following Rajoy's announcement.

Known as a "cassolada" in Catalan, from the word for "pot", these impromptu demonstrations have become increasingly common.

They are led by a new network of self-organising neighbourhood activists, known as the Committees to Defend the Referendum (CDR), with a presence in nearly every district of Barcelona.

"We were born on September 30," Ana Martinez, a CDR member from the working-class neighbourhood of La Verneda i La Pau, told Al Jazeera.

"We're a young movement," she added, surrounded by residents of all ages, including her two children.

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Martinez said the group originally started with four or five pro-independence residents of their neighbourhood who organised to support the referendum.

The activists wanted to camp overnight inside a primary school in La Verneda i La Pau to make sure it would be open for voting on October 1.

"This neighbourhood, you have to know, there aren't many pro-independence people," said Martinez. "Because of that, we thought police wouldn't come, but they did."

The Spanish Constitutional Court ruled the referendum illegal and ordered police to stop the vote while respecting the coexistence of the Catalan people.

As it became clear that Spain was sending national police and the civil guard, more residents went to the school overnight.

The next morning, nearly two dozen Spanish police vans showed up at the school.

A video recorded by the activists shows a seated, elderly man being hit by Spanish police on the head with a baton. The man is later seen bleeding from the wound.

Human Rights Watch said the Spanish police used "excessive force" to stop the referendum and called for an investigation into law enforcement's conduct.

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According to the Catalan government, 1,066 people were injured by police during the referendum, including 23 people older than 79.

The video footage also shows the aftermath of the raid.

Police allegedly ransacked the school while searching for ballot boxes, destroying classrooms and other facilities.

"The school was my school, and it's my daughter's school and will be my son's school, and it was destroyed by the police," said Martinez.

Nearly three weeks after the referendum, the school has still not been repaired, she added.

The organisation

Martinez said the CDR network has seen a huge uptick in membership since the October 1 referendum.

Many, even those who did not support independence, "wanted to support the right to vote", she added.

Today, posters from the separate CDRs are seen all over the city, announcing marches and calling for independence.

Each neighbourhood branch has its own Facebook and Twitter profiles, while members use encrypted chat applications to communicate.

"Right now, we have contact with all neighbourhoods, [even] in other cities, and all movements," said Martinez.

The network's name echoes that of Cuba's Committees to Defend the Revolution, who serve as the eyes and ears of the one-party state.

On Saturday, its members organised a joint event with a member of the far-left, anti-EU Popular Candidacy Platform party, a staunch advocate for Catalan independence.

When asked if the CDRs have a political stance, Martinez said the network was open to everyone from the left to right, "but not the extreme right or left … We just want a free Catalan republic."

'Excessive restrictions'

In recent days, the network's members have joined several large protests calling for the release of two pro-independence figures: Jordi Sanchez, of the Catalan National Assembly, and Jordi Cuixart, of Omnium Cultural, two civil society groups that often stage nonviolent, secessionist demonstrations.

Sanchez and Cuixart are currently imprisoned in Madrid without bail on charges of sedition related to their organising efforts.

Jordi Graupera, a Catalan author and researcher at Princeton university, told Al Jazeera they were "political prisoners" whose detention signifies a "lack of independent judiciary".

Spain's Amnesty International (AI) office released a statement calling the sedition charges "excessive" and asking for their release pending appearances in court.

AI spokesperson Ana Gomez said the rights group does not use the term "political prisoners" for lack of an international consensus on its definition. Instead, it opts for "prisoners of conscience."

Gomez said that AI does not yet consider Sanchez and Cuixart to be prisoners of conscience, as the judicial process is still open. She noted, however, that their imprisonment constitutes "excessive restrictions" on their political expression.

When asked if he feared an increase in protests after announcing the implementation of Article 155, Rajoy responded that his only fear was "not complying" with his obligations as a leader.

Yet, CDR activists in Barcelona said they had no intention of stop demonstrating until they reach their goal.

"No one said it would happen tomorrow," said Marti. "This is going to take some time."