In the first incident reported from southwest Delhi's Sagarpur area, three boys on a scooter were mowed down by a mini-truck, they said.
The victims were taken to the Deen Dayal Upadhyay Hospital where two of them were declared brought dead, while the third boy is undergoing treatment, the police said.
The deceased were identified as Firoz (17) and Monu (15). Their friend Rohit is undergoing treatment, they said.
Firoz was riding the two-wheeler. The trio were without helmets, the police said.
In the second incident, a truck allegedly hit a man on a motorcycle and then dragged the victim under its wheels in southeast Delhi's Sarita Vihar area. The deceased was identified as 41-year-old Gopal Prasad, the police said.
Prasad, who was a resident of Faridabad, died on the spot. The accused driver, Virendra Singh (24), was arrested, they said.