The Mayor of Barcelona urged the Spanish police to immediately end their violence “against the defenseless population.” Spain’s central authorities launched a massive crackdown on the Catalan independence referendum which they say is illegal.

At least 460 people have been injured in clashes between police and voters amid the ongoing independence referendum, Mayor Ada Colau tweeted, urging Spain’s law enforcement to immediately stop using aggressive tactics “against the defenseless population.”

READ MORE: Catalonia holds independence referendum amid violent attempts to thwart vote Live updates

In a separate statement, the Catalan health service reported treating 465 casualties, two of whom are in a serious condition in hospital.

Spain’s Interior Ministry said that nine police officers and three Civil Guards sustained injuries during the clashes.

Over 460 people injured in Catalonia already. As Mayor of BCN I demand an immediate end to police charges against the defenceless population https://t.co/412z6Jacap — Ada Colau (@AdaColau) October 1, 2017

Sunday’s Catalan independence referendum was marked by violent clashes between voters and the police, which attempted to block Catalans from voting, forcibly removing them from polling stations. The police repeatedly used batons and rubber bullets against civilians, as multiple footage from the scene indicates.