A teenage girl was among three more people arrested over a "brutal" suspected hate crime which left a teenage asylum seeker with a fractured skull and a blood clot on his brain.
Scotland Yard said the 17-year-old had been arrested on suspicion of attempted murder and violent disorder along with a 26-year-old man. A 23-year-old man was arrested in Croydon on Sunday on suspicion of attempted murder.
Detectives believe a group of eight people chased the Kurdish-Iranian teen in Croydon after discovering he was an asylum seeker “and launched a brutal attack".
Officers and paramedics found the 17-year-old boy with “serious head and facial injuries” who is now in stable condition in hospital. He had suffered a fractured skull and a blood clot on his brain.
The boy remains in hospital in a serious but stable condition, not believed to be life-threatening.
Detectives had already arrested four men and two women on suspicion of attempted murder and violent disorder, although they later released a 20-year-old woman without charge.
The incident has drawn widespread condemnation, with Tory minister Gavin Barwell describing the attackers as "scum".
London Mayor Sadiq Khan also condemned the attack, saying hate crime "has no place in London, Britain or anywhere else", while the Refugee Council said it was "disgusted" by the assault.
Labour leader Jeremy Corbyn also denounced it, saying he was "absolutely shocked at attack" and he fervently hoped he makes a full recovery."
The teenager, a Kurdish Iranian, was waiting at a bus stop with two friends outside The Goat pub in the Shrublands area when the group approached them.
After discovering he was an asylum seeker they chased him and launched a vicious assault, repeatedly kicking him on the floor and aiming blows to his head.
One resident of Shrublands Avenue, where the attack took place, said: "There was a group of roughly 10 people that was kicking and punching him, and the rest, another 10 or 20, were all just around watching."
They added: "You couldn't see who was hitting who."
They added that the victims was "getting absolutely beaten up - kicked, mostly in the facial area."
"He was getting kicked and punched by everyone," they said. "Then when they heard sirens they started to go. People that were there, witnesses, because they couldn't do anything against a group of 30 people, they had to wait until they moved off and that's when they managed to help him.
"That's eventually when the ambulance and police (arrived), and that was it."
Detectives are investigating whether some of those involved had been drinking in The Goat pub nearby.
Managers at the pub said they were "saddened" to hear of the incident, adding: "We do not in any way condone such action and we will do anything within our powers to help police to bring those that carried out this act to book. To the victim, we pray for his speedy recovery."
Chief Superintendent Jeff Boothe, Croydon's borough commander, called it a "savage attack" and said it was only the intervention of passers-by and the arrival of police that stopped it being worse.
The "close-knit community" has been left shocked by the ferocity of the attack, he added, and extra officers have been out and about to reassure people.
He said: "This is not usual for the area, it is out of the norm. This is not Croydon, Croydon is a very diverse community - they celebrate their diversity."
Mr Boothe added: "Hate crime is something which we understand can be very, very divisive. Croydon is culturally diverse and we need to continue to celebrate that."