"This inquiry needs to focus on whether it is faulty regulations or inadequate policing, or a combination of both, which is at the heart of the problem."
Committee chair and National MP Kanwaljit Singh Bakshi said the inquiry's draft terms of reference had been agreed, which were essentially to examine how gangs and criminals were getting their hands on illegal firearms.
"There is a big problem right now. And we hope to nail it down," he said.
Green Party criminal justice spokesman David Clendon said he was pleased all parties had supported the inquiry.
"This is not just about gangs. Certainly they are part of the problem ... but many of the major gun-related tragedies in New Zealand have had nothing to do with gangs ... we really need to get control of the availability of firearms.
"It's not a crisis, but certainly it is an urgent problem."
NZ First law and order spokesman Ron Mark, who has previously said an inquiry would be a kneejerk political response, said it was agreed that the inquiry would look at issues relating to the illegal possession of firearms in New Zealand.
"That is quite tight, and New Zealand First is very comfortable with that. We have gone through firearms reviews ... time and time and time again in New Zealand. And I think the issue that has popped up here are how are these weapons, and particularly military-style weapons, ending up in the hands of organised crime."
Mr Mark said it was clear that after the Christchurch earthquakes Australian gangs had increasing influence in New Zealand, and that had changed the culture of the criminal underworld.
Last week, Police Minister Judith Collins said she wanted to see a select committee inquiry into the availability of firearms, after the shooting of four police officers in Kawerau and the discovery of a cache of guns was found stashed in the ceiling of a South Auckland home, including 14 military-style guns, among them AK47s and M16s.