A Bangladesh Air Force training aircraft crashed into a school campus in the capital, Dhaka, shortly after takeoff on Monday, killing at least 31 people including the pilot and injuring more than 100, officials said.

Bangladesh is observing a day of mourning after at least 31 people were killed when a military jet crashed into a school. Many of the victims were students who had just come out of class when an F-7 jet crashed into the Milestone School and College in the capital Dhaka.

More than 170 people were injured after the training aircraft crashed, military officials said. The country’s interim leader called the loss “irreparable.”