At least 51 people, including 25 police were wounded Wednesday night, Armenia's health ministry said, after stone-throwing protesters attacked officers deployed outside a police building where the gunmen -- supporters of jailed opposition leader Zhirair Sefilyan -- have been holding four police officers hostage since Sunday morning.
Police hit back firing tear gas into the crowd, an AFP reporter said.
The protest continued into the early hours of Thursday as some 2,000 protesters built barricades in front of the cordons of baton-wielding riot police in flak jackets and helmets.
At dawn, riot police dispersed the crowd beating and arresting scores of demonstrators.
At least 15 opposition politicians from the moderate Civil Agreement party were arrested, the party leader, MP Nikol Pashinyan, told journalists.
Furious over the government's handling of the protracted hostage crisis, protesters have demanded Pashinyan be allowed to deliver food to the gunmen who have refused to accept provisions from the government.
The gunmen, who Sunday seized on a police regiment building in Yerevan's Erebuni district and captured a large arsenal of police weapons, freed four hostages Sunday and Monday, but were still holding four hostages as of Wednesday night.
The hostages include Armenia's deputy police chief General Major Vardan Egiazaryan and Yerevan deputy police chief Colonel Valeri Osipyan.
The attackers have demanded the resignation of President Serzh Sarkisian and the release of Sefilyan.
They issued a statement calling for Armenians to take to the streets against the government.
More than 1,500 anti-government protesters rallied in Yerevan Monday, calling for a bloodless resolution to the crisis.
Sefilyan -- the leader of small opposition group named the New Armenia Public Salvation Front -- and six of his supporters were arrested in June after authorities said they were preparing to seize government buildings and telecoms facilities in Yerevan.
A fierce critic of the government, he was arrested in 2006 over calls for "a violent overthrow of the government" and jailed for 18 months. He was released in 2008.
Last year, Sefilyan and several of his supporters were arrested again on suspicion of preparing a coup, but released shortly afterwards.
He then moved to Armenia to take part in the 1990s war with neighboring Azerbaijan for control of the Armenian-populated separatist region of Nagorny Karabakh.
Sarkisian, a former military officer, has been president of the tiny country of 2.9 million people since winning a vote in 2008 that saw bloody clashes between police and supporters of the defeated opposition candidate in which 10 people died.