Four persons have been killed and another seven injured in a serial explosion that rocked Nepal capital Kathmandu early this morning. According to a preliminary investigation, the explosions at three different places may have been triggered by a Maoist splinter group. However, no one has claimed responsibility for the explosions. While three persons were killed on the spot, the fourth one died while undergoing treatment at a hospital. Nepal emerged from a decade-long Maoist civil war in 2006 and the main group of the former rebels has joined the party that runs the government. The breakaway group of former rebels carried out a similar blast in Kathmandu in February in which one person was killed and two others were injured.