The airport has been sealed off by Russian troops
More than 30 people are being held hostage by heavily armed men - thought to be Chechen separatists - on a bus near an airport in southern Russia.
The masked gunmen seized the commuter bus, with 41 people on board, in the town of Nevinnomyssk, near the regional capital Stavropol, at 0700 local time (0300GMT). At least nine people - including some children - were subsequently released.
The hijackers - reportedly armed with a submachine gun, a hand grenade and TNT explosive - shot two people and demanded to be taken to the regional airport at Mineralnye Vody.
They are said to be seeking the release of five Chechens currently serving jail terms for a May 1994 bus hijacking in the same region.
A Russian anti-terrorist team is at the scene, and negotiations with the hijackers have begun.
BBC Moscow correespondent Caroline Wyatt says the negotiators have been told by the authorities to make no concessions, but also to ensure there is no loss of life.
Earlier, the acting chief of the local police department was shot and wounded while holding talks with the hijackers. Reports said one of the drivers on the bus was also shot and injured before being thrown out of the vehicle.
There are believed to be two gunmen involved in the hijack, but this is not confirmed.
President Vladimir Putin, who is at the Black Sea resort of Sochi preparing for a summit of former Soviet states, is being kept informed about the incident.
The Chechen rebel leadership has condemned the hijack.
Any actions targeting Russian civilians - "non-military people" - were unacceptable, a spokesman for separatist President Aslan Maskhadov told a Moscow radio station.
"I cannot say what nationality these people are, it could be anyone. We know absolutely nothing about their aims," he added.
Series of attacks
Mineralnye Vody, about 900 kilometres (550 miles) south of Moscow, is a popular resort town in the Caucasus Mountains.
Close to the border with Chechnya, where Russia continues operations to subdue separatist guerrillas, it has been the scene of several bus hijackings and bomb attacks in recent years.
Last March, 21 people were killed in a bomb blast at the market in the city.
In July 1994, four Chechens hijacked a bus with 41 passengers on board and demanded $15m. In a security forces operation to end the hijack, five hostages and a kidnapper were killed, 15 people were wounded and the surviving gunmen were arrested.
In 1992, armed hijackers seized a bus with 18 passengers on board and
demanded the release of two jailed friends, before fleeing to Chechnya where
they were given asylum by rebels.
-- Anonymous, July 31, 2001