Detectives were on Tuesday continuing to question a man in connection with a drive-by shooting outside a funeral service in Euston which left a seven-year-old girl seriously injured.
The shooting near St Aloysius Church left five others wounded after a gunman blasted a shotgun at mourners on Saturday afternoon.
Scotland Yard said the shooter fired from a black Toyota C-HR at around 1.30pm before it sped off.
Armed police arrested a 22-year-old man on suspicion of attempted murder after stopping a car in Cricklewood Lane, Barnet, at 4pm on Sunday. He remains in custody at a central London police station where officers continue to interview him over the shooting.
Meanwhile, the seven-year-old victim remains in a serious but stable condition in hospital.
A girl, 12, suffered a leg injury but has been discharged from hospital, while a 48-year-old woman sustained life-changing injuries, and three other women, aged 21, 41, and 58, were also wounded.
The victims were leaving a service for British-Colombian Sara Sanchez, 20, and her mother Fresia Calderon, 50, when the attacker fired into the crowd.
Ms Sanchez suffered from leukaemia for three years before succumbing to the disease after her mother died from a blood clot on arriving at Heathrow from Colombia.
Police are investigating a motive for the shooting but it is not believed to be linked to Colombian drugs gangs.
Father Jeremy Trood, who was conducting the service which was attended by around 300 people, said: “They were very scared, people sheltered in the church until the police said they could leave. It was pandemonium.”
The church re-opened yesterday and a mass was held with prayers for those injured in the shooting.
Forensics officers have scoured the scene for clues, collecting fragments of shotgun pellet, while detectives have collected CCTV footage and conducted house to house inquiries.
Sir Keir Starmer, who is the local MP, said police had assured him there would be “extra patrols and community support” following the “appalling” incident.
Mayor of London Sadiq Khan described the shooting as “deeply distressing” and said he was in close contact with detectives.
Anyone who witnessed the incident or who has information is asked to call 101, giving the reference 3357/14JAN.
To remain anonymous call Crimestoppers on 0800 555 111.