YEREVAN, Armenia -- Two more gunmen barricaded inside a police compound in Armenia's capital surrendered Sunday and one more was shot and wounded by security forces who are trying to end the two-week standoff, police said.

Of the 31 armed members of a radical opposition group who seized the Yerevan police compound on July 17, about 20 remained inside Sunday. Most of the wounded have been taken to hospitals for treatment and placed in custody.

The gunmen are demanding freedom for the leader of the group, who was arrested in June. The opposition group has sharply criticized the government of the former Soviet republic and called for people to take to the streets to force the president and the prime minister to step down.

Armenia's security service had given the gunmen until 5 p.m. on Saturday to surrender and said otherwise its forces reserved the right to open fire without warning. The sounds of gunfire and explosions were heard Sunday morning from the area around the police compound.

The standoff has dragged on in part because the government has wanted to avoid stoking further social unrest. Several thousand people have joined nightly rallies to support the gunmen, occasionally clashing with police.

On Saturday night, the demonstrators marched down Baghramyan Avenue toward the main government buildings and the presidential residence, but were stopped by riot police, who strung coils of barbed wire across the road. The demonstrators blocked traffic for about two hours, but dispersed peacefully early Sunday.

The gunmen killed one officer and wounded several others in their initial attack.

Police accused the opposition gunmen of killing a second officer on Saturday as he sat in a vehicle away from the compound -- but this was denied Sunday by a leading member of the armed group inside.

The gunmen had held four police officers hostage for a week before releasing them unharmed. They later seized four members of an ambulance crew, but the last two were allowed to leave on Saturday.