BHUBANESWAR, India (Reuters) - At least 16 people died on Sunday when a tourist boat capsized in the southern Indian state of Andhra Pradesh, officials said. 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. 