The boys allegedly drove to the venue on Saturday that was intended to hold a wake for Lorenzo Lemalu.
The driver began recording while his accomplice unloaded 30 rounds from a semi-automatic rifle.
However, the event had been cancelled shortly beforehand, meaning the Punchbowl venue in Western Sydney was unoccupied and no one was hurt.
Police arrested and charged the 17-year-old gunmen and a 23-year-old accused of assisting in the crime on Monday.
They announced the arrest of the second teenager on Thursday.
Taskforce Falcon commander Jason Box said the two boys were the latest in a series of young people involved in serious crimes.
"We've arrested 17 and 18-year-old women recently, females who have been involved in conspiracies to murder, who have conducted surveillance on potential targets, who were armed with weapons," he told reporters on Thursday.
"Young men and women that are willing to take on this serious crime.
"The issue is they don't know who is directing their actions and they don't know who they are targeting."
Organised crime figures are luring teenagers with money, the taskforce commander said, while many youngsters were also tempted by the opportunity to farm social media clout by posting about their crimes.
However, Det Supt Box warned it was not worth the jail time.
"I don't think they have any concept of what they're doing and the ramifications of what they're doing until they're caught," he said.
"There's no money that you could ask for to commit these offences. They're literally just destroying their lives for a short-term gain."
Premier Chris Minns echoed the sentiment, saying this kind of crime could never be excused.
"It's appalling that someone would attempt to recruit a child to commit these kinds of atrocious, violent acts," he said.
Det Supt Box said the best deterrent to stop vulnerable young people from being recruited to organised crime was for their parents and friends to speak with them.
14°C