Officers were speaking to Gemmell and charges were expected to be laid in due course.
"We are also speaking to a number of other people who our enquiries have led us to," Supt Basham said.
Police had worked "relentlessly" to resolve the situation, he said.
Anyone tempted to hide or dispose of the firearm should understand police would have a "relentless focus" on them, he said.
No police staff were injured and no shots were fired during the arrest.
Police were not in a position to say whether any shots had been fired from the recovered Glock.
Gemmell was likely to appear in court tomorrow.
Earlier today armed offenders squad members and a police dog squad swarmed on a Gore house.
Police established armed cordons on several intersections around a property in Surrey St.
RNZ reported police vehicles also converged on Crewe St at the intersection with George St.
There was also a heavy police presence at Diamond Peak Road, as police attended several other properties in Gore.
Police earlier blocked access to Invercargill Airport and searched a plane on the tarmac as part of the search for wanted man Gemmell, but a sighting of him on the plane turned out to be a false alarm.
A police spokeswoman said they conducted the search after a report of a possible sighting of Gemmell on an outbound plane about 8am.
"Police conducted a search of the plane and determined [Gemmell] was not on the flight."
