A suicide bomber set off an explosive-laden vest in a busy Baghdad square crowded with rush-hour commuters early Monday, killing at least 15 people and wounding dozens, officials said. The attack took place in Adan Square, in a predominantly Shiite part of the capital, and appeared to be the latest in a near-daily string of attacks carried out by Sunni Islamic extremists targeting the country’s Shiite majority. A police officer provided the death toll and said 45 other people were wounded. A medical official confirmed the casualty figures. Both officials spoke on condition of anonymity as they were not authorized to brief the media.