The deaths take the toll from six months of protests aimed at toppling the government to 27, with hundreds of others wounded in gun and grenade attacks linked to rallies.
Anti-government protesters have moved to the area immediately around Government House in the city's historic quarter as they try to press the Thai Senate to remove the caretaker administration and appoint a new prime minister.
Former premier Yingluck Shinawatra was ousted by a Thai court last week, but was swiftly replaced by the ruling Puea Thai party, who are refusing to bow to pressure saying they are the democratically elected government