Nigerian officials say 15 people were killed and 21 were wounded when a bus station was bombed Monday in the northeastern Nigerian city of Gombe. No group has claimed responsibility for the attack, but Boko Haram is known for targeting civilians, especially in the northeastern part of the country. Monday’s bombing was the second attack on the Gombe’s public-transportation system in recent months. In October, a car bomb at a bus stop killed 10 people. Over the weekend, Boko Haram released a gruesome video of the slaying of elderly civilians at a school with messages that denounced Western education.