The cars were heading to Hanumangarh from Sriganganagar before they collided with a private bus near Jhandawali village, police said.
Shrawan Kaur (45), Nakshatra Singh (45), his wife Rano Kaur (40) and his mother Jeeto (65) died on the spot while the injured were rushed to a nearby hospital.
The bodies of the deceased have been shifted to the hospital for postmortem, police said.