Explosions and gunfire are being heard in the Georgian capital, Tbilisi, as counterterrorism units storm a multi-storey apartment building on the outskirts of the city.
Georgia's state security service said on Wednesday that unidentified number of suspects holed up in one of the apartments opened fire on the troops that were conducting a large-scale operation in the area.
The heavy metal door to the suspects' apartment on the third floor was yet to be forced open 20 hours since the start of the operation.
At least one security officer was shot in the head. A doctor at the hospital where he received an emergency surgery told the reporters outside the facility that the patient was in a critical condition.
Nino Giorgobiani, the deputy head of administration at Georgia's state security service, said at a news conference that one suspect was arrested on Wednesday during the operation and the attempt to capture the rest of the suspects alive was ongoing.
"According to the preliminary information they are not Georgian nationals and they are members of a terrorist organisation," she said.
"It is important to note, that Georgia's counter-terrorism department has been conducting negotiations with them for several hours about surrendering but they rejected it.
"The members of the criminal group opened fire from an automatic rifle and threw hand grenades. The gunfire resulted in an injury of a member of the special force."
She also said that an investigation into the identities and alleged criminal links of the suspects was under way in and outside Georgia.
The intensive gunfight started at 5am local time on Wednesday, according to eyewitnesses.
Residents of the building said the suspects had been living in the building for two years.
The apartment block has been partially evacuated.
About 100 policemen and firefighters were mobilised at the scene, witnesses said.
The Georgian government held an emergency security meeting, but did not public statements on the ongoing situation.
The prolonged operation prompted criticism of the government from its political rivals.
"It is obvious that surveillance and planning of the operation were flawed. Neutralising one apartment should not have taken more than two hours," said Nika Rurua, a member of National Movement opposition party.
"There is a serious security problem in the country first of all from a surveillance aspect. These people have been in the building for more than two years and there is a big amount of weaponry in the apartment."