Three Chinese nationals have been found murdered in their apartment in Afghanistan ' s capital and another two living with them are still missing, officials say.China embassy in Kabul confirmed the incident in a statement released late on Friday. The statement did not say anything about the identity of the victims or the motive for the killings. The embassy called on the Afghan government to take necessary measures to investigate the incident and ensure the security of the Chinese nationals and institutions in the country, China's official news agency Xinhua reported. Police authorities in Afghanistan said on Saturday that the victims, two women and a man, were killed on Thursday but the incident was reported by a neighbor on Friday. "Initial investigations show they were ...killed by a gun with a silencer," Mohammad Zahir, head of the criminal investigation department said. "Two Chinese men are missing, we have launched an investigation to find them," he added. No one has claimed responsibility for the attack. Afghanistan has witnessed a rising tide of violence recently and there has been a sharp increase in civilian casualties in the country in the first half of 2013. The United Nations Assistance Mission in Afghanistan (UNAMA) said in a report on July 31 that civilian deaths were up 23 percent in the six months from a year ago. From January to June, the number of civilians killed in war-related incidents rose to 1,319 from 1,158 a year earlier. In the same period, 2,533 civilians were injured, compared with 1,976 in 2012.