Rampal Sagar (33), his wife Tarawati (32) and son Akash (14) were travelling on a bike when it was hit by a horse cart due to which they fell on the ground and were run over by a truck, they said.
While Rampal and Tarawati died on the spot, their son was injured and was rushed to a hospital, where his condition was stated to be stable, they said.
An FIR has been registered in this connection, police said, adding no arrests have been made so far.