ABUJA — Scores of people are missing and feared dead after an overloaded boat capsized in the northwestern Nigerian state of Kebbi on Wednesday with around 180 passengers on board, government authorities said.The incident took place in the Niger River early Wednesday local time when the boat left Niger state and was heading to Kebbi State​, according to Mary Noel-Berje, a spokeswoman for the Niger State government. Around 20 people have been rescued and four bodies recovered so far, she said, adding that the search and rescue operations are ongoing. Most of the passengers are from Kebbi State and are believed to be traders, Noel-Berje said. It was unclear what caused the boat to break up as it was traveling on the Niger River from Nigeria’s Niger state to the town of Wara in Kebbi state. Boat accidents are common in Nigeria, especially along the Niger River, due to overloading, poor conditions of the boats and collisions with debris underwater. — CNN with inputs from agencies