Four people were killed and seven others grievously injured when a van collided head-on with a bus in Tamil Nadu's Kanyakumari district on Friday morning. According to police, a van carrying a dance troupe from Tiruchendur to Kanyakumari collided with an oncoming bus at Vellamadam in Nagercoil- Tirunelveli, national highway.The bus was en route to Roshakulam from Nagercoil.Police said the van driver was also among the dead. Police also suspects that the driver of the van had dozed off leading to the crash.