TBILISI -- Georgia's State Security Service (SUS) says one soldier in its special forces unit has died in a hospital after being wounded during an operation against gunmen in a residential neighborhood on the outskirts of Tbilisi.

SUS spokeswoman Nino Giorgobiani on November 22 said three suspected “terrorists” also had been killed in the shoot-out in the Isani district of the Georgian capital.

At least one gunmen had been arrested and four other police officers had been injured in the 20-hour operation that began on November 21 and ended around 5:30 p.m. local time on November 22, officials said.

Giorgobiani said the suspects targeted by the operation were "foreign nationals" suspected of having ties with a "terrorist organization." She did not say where they were from or name any specific terrorist group.

But Georgian media reports said the gunmen were suspected of having ties with Islamic State (IS) extremists.

Georgia has conducted numerous counterterrorism operations in its Pankisi Gorge region, a mountain valley area in northeastern Georgia that borders Russia's southern region of Chechnya.

IS militants claimed in 2016 that they had established a training base in the Pankisi Gorge and were recruiting fighters there.

But Tbilisi has rejected those claims, and extremist militant violence in the Georgian capital, to the southwest of the Pankisi Gorge, has been rare.

WATCH: Mobile-phone video captures the moment Georgian security forces moved in on what they called a suspected terrorist group on the outskirts of Tbilisi on November 22.

Georgian Public TV reported on November 22 that the operation focused on an apartment belonging to a woman from Chechnya who had fled the Russian region during the war there in the late 1990s and moved to the Pankisi Gorge.

That report said the woman moved to Austria several years ago and had given the keys to the apartment to her 26-year-old son.

It said her son told authorities during questioning that he had given the keys to the brother of his wife and that, as far as he knew, the apartment had been vacant since May.

The operation began when police and special forces deployed outside the 10-story apartment building late at night.

Giorgobiani said the suspects refused an order to surrender and began shooting and throwing hand grenades at security forces.

Police and special forces called in reinforcements and continued to battle with the suspected militants, she said.

The sounds of gunfire and grenade explosions could be heard in the neighborhood through the night and into the early afternoon on November 22.

An RFE/RL correspondent at the scene in Tbilisi reported early on November 22 that security forces had surrounded the apartment building with at least four armored personnel carriers posted at strategic points.

At about 10:30 a.m. local time, in the midst of a heavy exchange of gunfire, an explosion rocked an apartment on the third floor of the building.

Thick smoke poured from the building for several hours, suggesting that the blast ignited a fire inside.

Firefighters were unable to reach the blaze while the security operation was continuing.

Authorities say residents of the surrounded apartment buildings were evacuated before the third-story explosion and fire.

Tbilisi's mayor says the city will reimburse residents in the neighborhood whose property was damaged as a result of the counterterrorism operation.

With reporting by Rustavi-TV, apsny.ge, APA, RIA Novostia, First Channel, and Interpressnews