The clashes followed a demonstration by residents from a social housing district in Seixal, on the other side of the River Tagus, and their supporters.

According to Tiago Garcia, a spokesman for the PSP’s Lisbon metropolitan command, four detentions were made following the clashes in Lisbon of residents of the Seixal neighborhood known as Jamaica.

Police had attempted to steer the group of protesters "onto the side of the road, but were greeted with stones and firecrackers", which "motivated a more muscular intervention", Garcia said. In response to the protesters, he added, "shots were fired with rubber bullets into the air, as a warning," to disperse the aggressors.

"They threw several stones from the sidewalk and firecrackers against the police,” Garcia said. “There was a need to disperse the protesters and the intervention [squad] felt the need to fire the shots. There were several members of the rapid intervention team, the traffic division and the intervention corps, he said, without revealing the number of officers involved in the occurrence.

Several police were injured by stones but with no need for hospital treatment, he said, but several vehicles were "damaged” by the stones and firecrackers.

He added that the police "remain in place to maintain order" and "the city is safe".

PSP patrol cars and riot squad officers downtown began to leave the area at around 8.30 pm.

Earlier, dozens of residents from the neighborhood known as Jamaica had protested in front of the Ministry of Internal Administration in Lisbon, against what they said were instances of police violence and racism.

The protest was stated following a police intervention on Sunday morning in Jamaica, after the PSP was alerted to "a disorder between two women" and sent a rapid intervention team from Setúbal. According to police, a group of men reacted to their arrival by throwing stones, injuring five civilians and one PSP officer slightly injured.

The PSP has opened an internal investigation into Sunday’s the police intervention “and all the circumstances surrounding it". As a result one detention was made in Jamaica on Monday morning.