Further details are expected to make public information linking donors to political parties over the last five years
The accident took place in Krishna river about 25 km (15 miles) from Vijayawada city, district administrative chief B Lakshmikantham told Reuters.
The administration was investigating what exactly caused the incident, but the initial probe found that the private boat operator did not have the necessary permission to ferry people, Lakshmikantham said.
Around 20 of the roughly 35 people on the boat were rescued and search operations were continuing, India's National Disaster Response Force said on Twitter.