The gunmen set a police vehicle on fire inside the headquarters, police spokesman Ashot Aharonian said on Monday. The vehicle is the third to have been burned at the site in two days.
The gunmen stormed the facility on July 17, killing a police officer.
They have been demanding the release of Zhirair Sefilyan, an opposition leader accused by the government of plotting civil unrest. Sefilyan was jailed in June over allegations of illegal weapons possession.
Also on Monday, thousands of people staged a rally in Yerevan to voice solidarity with the pro-opposition gunmen.
The assailants had taken nine people hostage but gradually released all of them.
Police have cut electricity to the station and are refusing to deliver food after the release of the last hostages.
Of the total nine people taken hostage, the gunmen released two soon after the attack and three more a day later. Four police officers were also released on July 23 after negotiations with the hostage-takers, police said.
Sefilyan, an ethnic-Armenian who was born in Lebanon and fought during the Arab country’s civil war of the 1980s, has served jail terms since 2006 on charges of attempting to overthrow the government.
He opposes President Serzh Sargsyan, who has been ruling the country of 2.9 million people since he won contested elections in 2008.
Background on this from Katehon:
In Armenia, we are witnessing a classic “Maidan” spike: nationalist gunmen plus liberals. Their success may lead to catastrophic consequences surpassing the Ukrainian ones: civil war in Armenia, the resumption of the Karabakh conflict, large-scale regional war. At the same time, Russia is unlikely to support the rebels in the conflict, especially against the background of improved relations with Turkey and Azerbaijan, respectively. Armenia is doomed to failure. However, this inability of Russia to act on Armenia’s behalf will ensure its withdrawal from the zone of influence of the Russian and Eurasian integration structures.