Four tractors were seized when some persons were illegally transporting sand under Vidavaluru mandal limits in Nellore district on Wednesday. The raid was conducted as part of the increased vigil on illegal sand mining in the district. Vidavaluru police said that the seized tractors would be handed over to the revenue authorities in the mandal for further inquiries. There have been many complaints against the illegal transportation of sand from different places in the mandal recently.