Police said the bus, carrying 70 passengers returning from the temple town of Ambaji to their villages in Anand district, flipped when the driver tried to navigate a sharp curve on the road at high speed in wet conditions caused by the late monsoon season.
At least 25 people were killed and 49 others injured in the crash, local sources confirmed.
Of the injured, 31 were said to be in serious condition.
ILKHA