MAIDUGURI, Nigeria, June 13 (Reuters) - At least 50 people drowned and several others were missing after an overloaded boat capsized in Nigeria's north central region, residents and state officials said on Tuesday. It was not immediately clear how many people were in the boat, but Kwara state government in a statement said the people were from five villages and rescue efforts for possible survivors were still underway. See here for a complete list of exchanges and delays