There was tension in Yerevan on Wednesday night as hundreds of demonstrators gathered to support gunmen holding several hostages in a police station in the Armenian capital.
The hostage-takers are seeking the release of an opposition figure who was arrested in June for alleged illegal weapons possession.
The police fired tear gas and detonated smoke grenades after protesters began throwing stones at them.
They also say they made 136 arrests among the demonstrators.
Wednesday’s violence began when protesters tried to force their way into the police station after they were prevented from taking in food for the hostage-takers.
A number of demonstrators were injured and police say several officers were hurt too.
At one stage shots were heard but the situation calmed down later in the evening.
Armenian media reported that more than 50 people sought medical treatment in Yerevan hospitals after the clashes.
Authorities in the ex-Soviet republic accuse the
detained opposition leader, Jirair Sefilian, of plotting civil unrest. He has accused the president of mishandling a long-running conflict between pro-Armenian separatists and the breakaway Azeri region of Nagorno-Karabakh.