Three men have been arrested over the killing of nine-year-old Olivia Pratt-Korbel, Merseyside police have said. The force said earlier on Sunday that a 34-year-old man from Liverpool had been arrested on suspicion of murder and attempted murder. He remains in custody and is being questioned by detectives. A 41-year-old man from Knowsley was arrested in the early hours on suspicion of assisting an offender and is also in custody. On Sunday evening, Merseyside police said a third man, aged 29, had been arrested on suspicion of assisting an offender and was in custody, after officers carried out warrants at two addresses in the Liverpool area. Merseyside police previously arrested two men, a 33-year-old from Dovecot and a 36-year-old from Huyton, on suspicion of murder and two counts of attempted murder, but released them on bail a week ago. Olivia was fatally shot in the chest at her home in Dovecot at about 10pm on 22 August as her mother, Cheryl Korbel, tried to stop a gunman forcing his way through her front door while he chased a convicted burglar, Joseph Nee. Korbel sustained a gunshot wound to the wrist, and Nee was shot in the leg and torso. Neither of the men who entered the home had any links to Olivia’s family. The killing occurred 15 years to the day since the fatal shooting of schoolboy Rhys Jones in Liverpool. The force’s head of investigations, DCS Mark Kameen, said on Sunday: “I continue to urge anyone who has information that can help our investigation into Olivia’s tragic murder to please come forward so we can bring those responsible to justice. “A number of people have been arrested in respect of this investigation. However, we still need the public’s help in ensuring that we can a build a strong evidential picture so justice is served for Olivia and her family. “With this, I appeal for those who may have information, no matter how small, that could continue to help our inquiries to contact us directly or anonymously and we will do the rest.” The force released CCTV footage this week of the gunman running from the house. Kameen said forensic investigators had concluded that two guns were used during the attack but neither had been found. On Tuesday, the opening of the inquest into Olivia’s death heard how an armed police officer tried to save her life, pressing his hand on her wound as she was taken to hospital in the back of a police car. Her family have urged anyone with any information to “do the right thing” and come forward. They said: “If anyone knows anything, now is the time to speak up. It is not about being a ‘snitch’ or a ‘grass’, it is about finding out who took our baby away from us.” Olivia’s killing was the third fatal shooting in Liverpool in the space of a week, prompting the launch of Operation Miller, a crackdown on organised crime. Ashley Dale, a 28-year-old council worker, was shot outside her home on 21 August, and Sam Rimmer, 22, was shot in the Dingle area on 16 August. On Saturday, a minute’s applause was observed in memory of Olivia at the Merseyside derby between Liverpool and Everton. A banner, which was half blue and half red to signify the colours of the two teams, was unfurled, reading: “Enough is enough: Our city in unity.” A funeral mass will be held at St Margaret Mary’s church in Dovecot on 15 September, followed by a private burial. Her family have asked mourners to wear a “splash of pink” for the service. A crowdfunding page set up to support Olivia’s family has raised more than £40,000. Anyone with information about the incident is asked to direct message @MerPolCC on Twitter or contact Crimestoppers on 0800 555 111.