By Hasmik Mkrtchyan

YEREVAN (Reuters) - Police on Wednesday clashed with hundreds of demonstrators who had gathered in a show of support for gunmen holding several hostages in a police station in the Armenian capital Yerevan.

The police fired tear gas and detonated smoke grenades after protesters began throwing stones at them.

A crowd of several hundred had earlier gathered outside the station to express support for the group, which has been holding the hostages since Sunday.

The hostage-takers' main demand is for the release of Jirair Sefilian, an opposition leader whom authorities in the ex-Soviet republic have accused of plotting civil unrest. Sefilian was jailed in June over allegations of illegally possessing weapons.

Wednesday's violence began when demonstrators tried to force their way into the building after the police refused to take in food brought by the demonstrators for the hostage-takers.

The police told Reuters that several policemen had been injured. A Reuters witness also saw a number of injured demonstrators.

Shots were also heard during the clashes, although it was unclear who had fired them or whether anyone had been hit. The situation appeared to be calming down towards late evening as demonstrators dispersed.

One police officer had been killed and two wounded when the armed men seized the police station on Sunday. [nL8N1A306D]

Sefilian, a former military commander, has accused President Serzh Sarksyan of mishandling a long-running conflict between pro-Armenian separatists and the breakaway Azeri region of Nagorno-Karabakh.

A Moscow-brokered ceasefire halted four days of violence in

the South Caucasus region on April 5, the worst flare-up in

years, but sporadic shooting persists at night and some deaths

have been reported.

(Reporting By Hasmik Mrktchyan, writing by Jason Bush)