A 33-year-old man, from Dovecot, was arrested by armed officers on Friday, a day after a 36-year-old man, from the Huyton area, was held after an operation also involving armed officers.
Olivia Pratt-Korbel was shot on Monday night after a gunman chased his intended target, who has been named as convicted burglar Joseph Nee, into the family home in Dovecot, also injuring her mother Cheryl, 46.
Assistant mayor of Liverpool, Harry Doyle, said people have come forward with information because they “want to see justice” for the little girl and her loved ones.
He told BBC Breakfast: “Our community is still obviously extremely shook by what’s took place.
“There’s certainly a sense of hope and relief, with the announcements of the two arrests made so far.
“But the community really has pulled together this week.”
On Saturday, Merseyside Police reiterated their appeal for people to come forward with names, warning “silence is not an option”.
The force tweeted: “A simple request – share this far and wide, to everyone you know, and ask them to share if further still, so that there’s no hiding place for anyone involved in the murder of little Olivia.
“We need names. Silence is not an option.”
The 33-year-old suspect was arrested in Lunsford Road on Friday on suspicion of Olivia’s murder and two counts of attempted murder.
Merseyside Police released aerial footage of the moment the 36-year-old was arrested – on suspicion of Olivia’s murder and two counts of attempted murder – by armed officers on Thursday.
In the clip, officers can be seen leading the man away due to heat signature technology.
It came after neighbours described seeing armed police “all in black with balaclavas on and machine guns” descend on a block of flats.
The force has also released an image of a black Audi Q3, which they believe is the same car used to take 35-year-old Nee to hospital.
The car has been seized and detectives are appealing for information from witnesses who saw it in the days leading up to the shooting, or have information about its movements afterwards.
Olivia’s family have urged people to “do the right thing” and 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.”
A £500,000 package of support announced by the Home Office “doesn’t touch the sides” and what the community affected in Liverpool needs is “long-term solutions”, Mr Doyle said.
Some £350,000 will be used to expand a pilot scheme as part of efforts to tackle organised crime in Merseyside, while £150,000 will provide trauma and mental health support in the Liverpool and Knowsley areas, the Government announced.
Mr Doyle said budgets had been “decimated over the years”, including those for youth grants.
He said: “What our community needs is long-term solutions and funding support solutions for the kids here on the street who were Olivia’s friends.”