British police say as many as 20 people may have been involved in an attack on a 17-year-old Iranian-Kurdish asylum-seeker in south London.

London’s Metropolitan police released three images Monday of people they wish to question in the attack. Eight are already being held on suspicion of attempted murder.

Police say a group of youths approached the teen at a bus stop Friday night and questioned him. Upon learning he was an asylum-seeker, they chased him through the streets and beat him. The attack only stopped after police sirens could be heard and bystanders intervened.

“It is understood that the suspects asked the victim where he was from and when they established that he was an asylum seeker they chased him and launched a brutal attack,” the Reuters news agency quoted Detective Inspector Gary Castle as saying.

Castle said the teen “sustained serious head and facial injuries as a result of this attack, which included repeated blows to the head by a large group of attackers.” He remained hospitalized in serious but stable condition. CBS News partner network Sky News quoted authorities as saying he was left with a fractured skull and blood clot on his brain.

Political leaders have condemned the attack, with Conservative Party lawmaker Gavin Barwell describing the attackers as “scum.”

London Mayor Sadiq Khan condemned the attack, which he said “has no place in London, Britain or anywhere else,” and vowed the attackers would be brought to justice.

In the aftermath of the June 2016 vote to leave the European Union, Britain saw a surge in xenophobia expressed in taunts, threats and worse. For many, foreign- and native-born, the U.K. suddenly became a much scarier place.

“Before Friday we lived in a tolerant society,” Oana Gorcea, a 32-year-old Romanian who had been in Britain since she was a teenager, said last year in the wake of the vote. “I’ve been here 13 years, but I’ve never felt like I had to hide where I came from. But from Friday, things completely changed.”

Much of western Europe has seen a rise in xenophobic crime and rhetoric in recent years, as far-right political groups seize upon fears over the influx of many thousands of refugees and migrants from war- and poverty-plagued nations in the Middle East and north Africa.

Source: CBSN