Those killed belonged to one family of Surat district. They were returning to Surat after offering prayers at the popular Pavagadh temple when the accident occurred late on Sunday night around 40 km from here.
A bus driver swerved his vehicle to avoid a collision but it overturned and hit a Sport Utility Vehicle moving in front, killing eight persons, Karjan police station Sub-Inspector JY Chauhan said.
The drivers of two cars following the bus also lost control and rammed the damaged vehicles, killing a woman and injuring three others.
Highway traffic was disrupted for over an hour due to the accident.
The injured were admitted to a private hospital at Karjan in a critical condition, Mr Chauhan said. The bodies have been sent for post-mortem.
Fourteen pilgrims returning from Pavagadh were killed in another accident on the Dholka-Bagodara road in Ahmedabad district on Friday night.