In a head-on collision between two buses on Monday, four persons were killed and 20 others injured on Dhaka-Mawa Highway at Nimtoli area of Munshiganj district.The collision between the Dhaka bound passenger bus Prachesta Poribohon and the Mawa bound passenger bus Gangchil Poribohon claimed the lives.The identities of the deceased could not be ascertained yet.Yeardous Hasan, officer-in-charge of Sirajdikhan Police Station, said two buses of Gangchil Poribohon and Prachesta Poribohon collided head-on near Nimtoli area around 1:30pm, leaving the four people dead on the spot.The injured were taken to different hospitals of Dhaka, he added.