The incident occurred this afternoon when the seven mandal Congress leaders from Timuku village were on way to Vijayanagaram to attend the wedding of Andhra Pradesh Congress chief Botsa Satyanarayana's daughter, police said.
The driver and two Congressmen -- Venugopal Rao and Nagi Reddy -- died on the spot, they said, adding, the four injured were rushed to Kakinada government hospital.
A case has been registered and investigation is on, they said.