Speaking live from the scene, RFE/RL's Yerevan bureau correspondent Hrach Melkumian said special police forces -- waving truncheons and throwing blank grenades -- charged up to 3,000 demonstrators on Marshal Baghramian Avenue, the Armenian capital's main thoroughfare.
"People are panicking and are running down Marshal Baghramian Avenue. Police are using water cannons. They have taken away the barbed wire that was in front of the parliament building and started charging the demonstrators," Melkumian said.
As soon as the security raid started, opposition supporters spread out in various directions and attempted to break through the police cordon. Some found refuge in smaller streets, others in private houses nearby.
Police today confirmed the operation, saying only that several people were injured and others detained during the night raid.
Armenia's Noyan Tapan news agency today quotes Yerevan city health officials as saying 16 demonstrators were hospitalized. Armenian state television showed pictures of policemen being assaulted by people identified as protesters and security officers receiving medical treatment. It gave no details of civilian injuries.
Armenian private media say several journalists were among the detainees.
In comments broadcast on state-controlled television today, Interior Ministry spokesman Sayat Shirinian accused the protesters of provoking security forces.
"Police repeatedly warned demonstrators that their unlawful actions would be met with adequate reaction if they were to continue. But, despite this, the transgressors went on for quite a long time with their antisocial actions. On top of this, in response to [our] warnings, they started moving menacingly toward police forces," Shirinian said.
Shirinian said protesters assaulted security officers with stones and petrol bombs while shouting antigovernment slogans and calling for the violent overthrow of the existing regime.
The opposition denies these claims.
One female demonstrator, speaking to RFE/RL, described the security crackdown. She said the streetlights went out suddenly and that the police moved in without prior warning.
"We saw these water cannons coming toward us and they starting drenching us. Then special police forces started throwing [blank] grenades at the crowd. We heard explosions and ran away in panic. They started chasing us with truncheons," she said.
The Organization for Security and Cooperation in Europe (OSCE) gave a mixed assessment of the overnight unrest. In comments made to RFE/RL's Armenian Service, Ambassador Vladimir Pryakhin suggested that both protesters and police forces were to blame for the violence.
"We don't share the opinion that the demonstration was purely peaceful, because all sorts of provocative statements were being made and stones were being thrown [at police forces]. But that's not the point. We are against any kind of violence, and we conveyed our concerns with this regard personally to [President Kocharian]," Pryakhin said.
RFE/RL's Yerevan Bureau reports that the offices of Armenia's main opposition parties were raided during the night and several activists detained. Some, such as lawmaker Shavarsh Kocharian of the Justice (Artarutyun) alliance, were released shortly after.
None of the main opposition leaders was detained.
Speaking to RFE/RL's Armenian Service early today, National Unity Party Chairman Artashes Geghamian said he was among the protesters on Marshal Baghramian Avenue and that he escaped with only slight injuries.
"Everything was carefully planned to sow panic among people. [Police] started beating protesters indiscriminately with truncheons, regardless of who they were -- women, children, or old people. I went to a group of policemen and told them: 'I am Geghamian. Beat me up if you want.' Strangely enough, they hit me only twice and let me go," Geghamian said.
Yesterday's march marked the culmination of four days of anti-Kocharian protests led by the Justice alliance and the National Unity Party.
Justice and National Unity have accused Kocharian and the three parties in the coalition government of rigging last year's presidential and legislative elections and insist his leadership be put to a national vote of confidence.
Kocharian denies any wrongdoing.
Police today prevented Justice leader Stepan Demirchian from giving a planned press conference. Representatives of the three coalition partners are due to meet with Kocharian to discuss the political situation.
In a bid to defuse the mounting political tension, the Dashnaktsutyun Armenian Revolutionary Federation -- one of the three partners in the ruling coalition -- last week proposed that Justice and its allies have a say in domestic affairs through the National Security Council.
However, the opposition rejected the offer.
In what is seen by some as a sign of possible cracks in the country's top leadership, lawmakers of Dashnaktsutyun and the two other coalition partners -- the Republican Party and Rule of Law (Orinats Yerkir) -- unexpectedly walked out of yesterday's parliamentary session.
Dashnaktsutyun parliamentarian Vahan Hovanessian justified the boycott by saying all three coalition partners wanted to avoid possible violence between their supporters and anti-Kocharian street protesters.
The move was greeted skeptically by the Justice leadership, but was welcomed by National Unity party leader Geghamian, who said it signals the end of Kocharian's rule.
In comments made to RFE/RL's Armenian Service today, Geghamian said the opposition remains undeterred, despite the overnight crackdown.
"This once again proves that Kocharian cannot stay in power and must go," he said.
Meanwhile, Armenian authorities have cleaned up Marshal Baghramian Avenue and blocked Yerevan's central Freedom Square, the main venue for opposition rallies.
Whether the opposition will be able to stage further antigovernment rallies in the coming days remains unclear.
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