Spain's central government demanded Sunday that Catalonia's president Carles Puigdemont call off an independence referendum, dismissing the vote as a "farce", as national police moved in to stop it.
"Puigdemont and his team are solely responsible for all that has happened today and for all that can happen if they do not put an end to this farce," Madrid's representative in Catalonia Enric Millo told a news conference.
Catalonia's emergency services said they had treated 38 people hurt during a police crackdown at polling stations, Most had suffered bruises, dizziness and anxiety attacks.
Spain's interior ministry said 11 police officers were injured in clashes with protesters. Demonstrators had thrown rocks at police, it added in a Twitter message.
Police fired rubber bullets in Barcelona as they charged protesters who wanted to vote in the independence vote which was banned by Spain's central government and the courts, witnesses told AFP.
Millo, however, said police officers were acting with "proportionality".
He also said Catalonia's regional police force had sought help from national police to block voting from happening at 233 polling stations.
"This is a gesture than honours them," Millo said, just hours after he complained that Catalan regional police were not doing anything to prevent polling stations from opening.
Spain's Interior Minister Juan Ignacio Zoido also urged Catalan authorities "to stop this genuine madness", adding that officers from the national force and the Guardia Civil had "neutralised" 70 polling stations.
The Catalan government says it had prepared just over 2,300 polling stations for the vote.
The Spanish government had said on Saturday that it had already sealed more than half of them.
Zoido also said the computer system which Catalan authorities say they have set up to prevent people from voting twice in the referendum "does not work".
Officers from Spain's Guardia Civil police force visited the Catalan government's communications hub in Barcelona on Saturday, cutting its connections with polling stations and access to software that could have allowed an online vote.