The victims, residents of Kompalli area in Hyderabad, were on their way to Kaleshwaram town in the van to take a holy dip in Saraswathi river.
The cement mixer truck, coming from opposite direction, collided with the van, resulting in death of four passengers at the spot, police said.
The injured were shifted to a private hospital in the town, where the condition of three is reported to be critical, they said.
Kaleshwaram, which houses a famous Lord Shiva temple, is about 277 km from Hyderabad and 125 km from here.