Police are taking a detailed look at more than 4000 stolen firearms licence documents that have now been recovered in a bid to work out how many lawful gun owners have been affected.

Personal details, including names and addresses of firearms owners, were among the documents allegedly stolen from the disused Auckland City police station.

The documents relate to people in the Auckland city centre area who renewed or got a new licence between 2015 and 2017.

Some fear the documents could serve as a shopping list for criminals wanting to steal lawfully obtained guns.

Auckland District Commander, Superintendent Karyn Malthus, believed the Vincent St burglary occurred in early May but police didn't learn of it until later that month, on May 25.

Police are now contacting people identified in 444 data sheets containing firearms licence holders' name and address details.

Those firearms owners were being advised of the breach and that the documents had been recovered, Malthus said.

"Police will continue to contact affected people over the coming days," she said.

"More broadly, police will be contacting all firearms licence holders in the Auckland City Police District via mail to advise them of this incident."

To help with this, police have set up a hotline people can call on 0800 462 379 and an email address: [email protected].

The burglary is now the subject of a major criminal investigation.

So far police have identified more than 2000 documents which record only address details.

But it was too early to understand how many people had been named in the documents, Malthus said.

"Police undertake daily monitoring of any incidents involving firearm licence holders, which includes theft or burglary reports," Malthus said.

That included two firearms related burglaries in the Auckland Central Area since the theft of the documents.

The first took place in Stonefields on May 22 and in Mt Albert on June 6, and the offenders have been arrested for both matters.

One incident appeared to have been opportunistic and the other a repeat burglary, Malthus said.

"There is no evidence to suggest that they are related to the Vincent Street burglary, however the police investigation team will also look closely at those burglaries and the offenders involved," she said

"We can advise that at this stage there have been no incidents linked to information obtained from the burglary of the old Auckland Central Station."

Those contacted by police will be told about the theft advised on the next steps in the process.

"We continue to advise firearms licence holders to remain vigilant and ensure they have good security measures in place," Malthus said.