At least 51 people were killed after a boat sank in Nigeria's northwestern Sokoto state Thursday, as rescue teams continued searching the waters for victims and possible survivors, according to local accounts.

Such accidents are common on Nigeria's busy rivers and waterways, often caused by overloaded boats, poor maintenance or failure to comply with safety regulations.

Scores of people drown each year.

"The situation is bad," said Ibrahim Musa, a former councillor of Gorau village, in Goronyo district, where the accident occurred.

"We already buried 46 bodies, and five others have just been brought out of the river."