A brother-sister duo was killedin a road accident on the Mumbai-Ahmedabad Highway in Dahanu area of Palghar district on Friday afternoon, police said.The two, identified as 24-year-old Chainesh Dombare and his sister Ramila (14), hailed from Ganjad-Deogav area of Dahbipada, an official said."The two were on a motorcycle when a truck coming from the opposite direction hit them, killing both on the spot. Truck driver Asghar Khan (54) was arrested," the Dahanu police station official said.