Pro-opposition gunmen locked in a protracted standoff with police in the Armenian capital Yerevan have taken four medical staff hostage, officials said, after a shootout left five people wounded.

Two doctors and two nurses were held after entering a police compound seized by the assailants 10 days ago to treat two gunmen injured in clashes.

“The doctors who went into the captured territory to assist two members of the armed group who refused to go to hospital have been taken hostage,” police spokesman Ashot Aharonyan said. “The police are taking steps to free the doctors through negotiations.”

Supporters of the opposition demand the resignation of Armenia’s president, Serzh Sarkisian. Photograph: Hayk Baghdasaryan/EPA

A health ministry spokesman said later that one of the nurses had been freed. “Three other health professionals, two doctors and a nurse, are still being held,” he said.

Gunmen – supporters of jailed opposition leader Zhirair Sefilyan – stormed a police building in Yerevan on 17 July, killing one officer, taking several more hostage and seizing a store of weapons.

Over the weekend they released the final four police officers being held captive but remained holed up inside the police building surrounded by law enforcement officers.

The group has demanded the resignation of the ex-Soviet nation’s President Serzh Sarkisian and the release of Sefilyan.

The lengthy standoff has shaken the tiny Caucasus republic and sparked clashes between police and protesters furious over the handling of the incident.

Sefilyan – the leader of a small opposition group named the New Armenia Public Salvation Front – and six of his supporters were arrested in June accused of preparing to seize government buildings and telecoms facilities in Yerevan.

A fierce critic of the government, he was previously arrested in 2006 over calls for “a violent overthrow of the government” and jailed for 18 months. He was released in 2008.

Sarkisian, a pro-Russian former military officer, has been president of the country of 2.9 million people since winning a vote in 2008 that saw clashes between police and supporters of the defeated opposition candidate in which 10 people died.