Thousands of protesters stood firm outside a Spanish court in Barcelona after night fell Thursday, continuing to shout demands for the release of a dozen regional officials arrested in connection with a planned vote on Catalan independence.

Spanish authorities maintain the referendum scheduled for Oct. 1 is illegal and are challenging its constitutionality. But Catalan pro-independence groups also are digging in their heels as they fight for what they say is their right to vote.

The demonstrators who spent the day outside the Catalan Superior Court of Justice, a branch of the Spain’s national legal system, answered a call by pro-independence civic groups to stage long-term street protests against the surprise crackdown by police the previous day.

As the sun set, a large crowd sang, waved pro-independence flags and held banners proclaiming “Democracia!” (Democracy!) Unlike the previous night, when there were scuffles with police and patrol cars were vandalized, the mood remained festive.