Pro-independence protesters in Barcelona. Albert Garcia / EL PAÍS

There were new disturbances on the streets of Barcelona on Wednesday night, when violent protesters set fire to a dozen vehicles, hurled acid and petrol bombs at riot officers, and reportedly aimed rockets at a police helicopter that was hovering over crowds.

More than 50 fires were reported in the downtown area of the Catalan capital according to city officials. There were 33 arrests and nearly 100 people required medical assistance – including 30 law-enforcement officers – following the five-hour standoff.

Third day of protests in Barcelona (Spanish text).

The fresh night of street violence came in the wake of the Spanish Supreme Court’s decision, made public on Monday, to sentence nine Catalan separatist leaders to prison terms for their role in the illegal breakaway bid of 2017.

The independence movement had widely anticipated an adverse decision and organized mass protests that included blockading Barcelona’s busy airport on Monday. The demonstrations have been largely peaceful, but the Spanish government has pointed to several “coordinated groups that are using street violence” to create a sense of chaos.

The scenes were similar to those seen on Tuesday night, except there were fewer, more aggressive protesters. The violence began at around 9pm, following a peaceful demonstration by a crowd of around 22,000 people at the intersection of Gran Via and Marina street. Small groups of protesters walked over to the headquarters of the home affairs department, which was being protected by officers from the Catalan law enforcement agency Mossos d’Esquadra, and began shaking the metal fence panels while calling for the resignation of department chief Miquel Buch.

The mood quickly became more tense, and the Mossos used their vans to force the protesters away from the spot while the latter hurled objects at them. Meanwhile, trash containers were set alight on the corner of Casp and Nàpols streets, and there were moments of panic when the flames reached a nearby commercial establishment.

On Roger de Flor street, a man with a baby in his arms came out of a building shouting at the protestors after seeing the flames approaching his home. Bars and hotels shut their doors and pulled down the blinds while patrons watched the running battles taking place outside. Several people were injured at this spot, including at least one young woman who was hit in the head with a rubber bullet. “I don’t really know how it happened,” she told the medical team that came to help her.

Calle Roger de Flor. Un padre sale de su casa con su bebé en brazos a toda prisa huyendo de las llamas y el humo que amenazaban su vivienda. Barcelona 2019, con la colaboración de la Generalitat, y permisividad del Gobierno central. #TsunamicDemocratic pic.twitter.com/jJoszF79Ss — Naranjito 🍊 (@PedroOtamendi) October 16, 2019

By that point, there were fires in several streets of the Eixample district. Deputy Mayor Jaume Collboni on Thursday said there were more than 50 in that area alone.

Nearby, the fire from several burning containers reached a dozen parked vehicles and a motorcycle, which also went up in flames. The cars were parked near a gas station that was under police custody.

Catalan police sources said that some protesters had aimed rockets of the kind used in fireworks displays at one of the helicopters flying overhead. They also reported that some officers were targeted with large rocks and acid.

On Gran Via, the clashes became so intense that at around midnight Mossos officers were forced to retreat, drawing cheers from the protesters who decided to end the street battle there and move to a new spot on the corner of Passeig de Sant Joan and Diagonal.