The incident occurred last night when the victims were on their way to Jaipur from Niwai in Tonk district, SHO Chaksu Rohitash said.
Shivshankar, his wife Indira, and elderly mother Bhuli Devi were killed while two teenage sons Harshit and Datraj injured in the mishap, he said.
The bodies were handed over to family members after post-mortem today.