39-year-old business man K Malaichamy was returning to Chennai with his wife Anitha(27), four-year-old Charan(4),his infant daughter and mother-in-law Nageswari after celebrating Diwali at Madurai, they said.
He lost control of the car when they were nearing Viralimarai and collided with the bus, police said.
Nageswari and charan died on the spot and Anitha died while being taken to the hospital.
Malaichamy and his daugher were admitted to a private hospital here in a serious condition.