One police officer was killed and two others wounded early on Sunday when members of an Armenian radical opposition group seized a police station in Yerevan, demanding the release of its leader arrested last month for allegedly plotting an armed revolt.

Varuzhan Avetisian, one of the members of the Founding Parliament movement that stormed the police building in Yerevan’s southern Erebuni district, said the “rebellion” is also aimed at forcing President Serzh Sarkisian to step down.

Avetisian told RFE/RL’s Armenian service (Azatutyun.am) that several law-enforcement officers and Founding Parliament members were wounded when police tried unsuccessfully to retake control of the building. Residents of nearby apartment buildings said they heard several explosions in the early hours of the morning. “There were also many gunshots afterwards,” one of them said. The Armenian police and other services cordoned off the area later in the morning.

The National Security Service (NSS) said the attackers are holding hostage police personnel inside the building. “Negotiations are being conducted with the armed individuals with the aim of organizing their surrender to the Armenian authorities,” the NSS said in a statement. Another NSS statement released later in the day said one police officer was killed and two others wounded in the attack.

“Armenian law-enforcement bodies fully control the situation and are taking all necessary measures to resolve it,” it said. Nikol Pashinian, an Armenian mainstream opposition leader, visited the Erebuni police station and spoke with the leaders of the armed group. He told reporters afterwards that he saw about 25 people inside the building and that 8 of them were police officers held there as hostages.

One of the policemen was freed after his health condition deteriorated, Pashinian said. Zhirayr Sefilian, Founding Parliament’s top leader, was taken into custody on June 20 after allegedly acquiring large quantities of weapons and forming an armed group to seize government buildings in Yerevan. Law-enforcement authorities also announced the arrest of six other individuals. Sefilian was afterwards formally charged with only illegal acquisition and possession of weapons and ammunition.

The outspoken oppositionist and his associates strongly deny the charges as politically motivated. The Founding Parliament has repeatedly demanded its leader’s release, saying that he is prosecuted because he planned to thwart Armenian territorial concessions which President Sarkisian allegedly plans to make to Azerbaijan.

Late last year, Founding Parliament teamed up with several other small opposition groups to try to force Sarkisian to resign with a series of anti-government rallies in Yerevan. The campaign fizzled out due to poor attendance of those rallies. Early this year Sefilian’s group tried in vain to make another push for regime change. It again failed to win over mainstream opposition parties represented in Armenia’s parliament. Less than two weeks before his arrest, Sefilian announced plans to set up a new opposition movement called the National Resistance Committee. The Lebanese-born oppositionist said it will try to topple the government “with the help of the people and the army.”