Separately on Thursday, a bomb blast killed four government employees commuting in a minibus in the capital, Kabul, police said. Ferdaws Faramarz, a spokesman for the Kabul police chief, said one woman was among the dead and nine other people were injured in the attack in the northern part of the city.
No one immediately claimed responsibility for the Kabul attack, but government officials have been targeted before. On Monday, another bombing of a minibus carrying government workers in Kabul killed three women and a three-year-old child, injuring 13 others, according to security officials.
Afghanistan is experiencing a nationwide rise in bombs, targeted killings and other violence as peace talks in Qatar between the Taliban insurgents and the Afghan government stall.
The local affiliate of the Islamic State group has claimed responsibility for some of the violence, but many attacks do not go back, with the Afghan government blaming the Taliban. The rebels have denied responsibility for most of the attacks.
The attack in Kabul comes on the same day that Russia hosts the first of three international conferences aimed at starting the peace process before a deadline of May 1 for the final withdrawal of US and NATO troops from the country.
The Moscow conference is seen as a critical first step towards peace. Key players are participating, including US peace envoy Zalmay Khalilzad, Afghan national security adviser Hamdullah Mohib and Taliban co-founder Mullah Abdul Ghani Baradar, who will lead a ten-member delegation. Representatives of Pakistan, Iran, India and China are also participating.