MOSCOW — Militants who attacked a police building in the Armenian capital, Yerevan, killing one person, remained holed up with a number of hostages for a second day on Monday, demanding that the government resign and that it release an opposition leader.

Two hostages were released overnight on Monday after intense negotiations, the National Security Service of Armenia said in a statement, and special forces helped release two others a day earlier.

Those who were still believed to be held included the deputy head of Armenia’s national police, Maj. Gen. Vardan Egiazaryan, and the deputy head of Yerevan’s police, Col. Valery Osipyan, according to local news websites.

The confrontation resulted in one death on Sunday during the initial capture of the building. A police officer, Col. Artur Vanoyan, was killed and three others were wounded, the local news website Panorama.am reported.