At least 20 people have been killed after a Bangladesh Air Force jet crashed into a private school campus in the south Asian country’s capital, Dhaka, on Monday.

Bangladesh, in shock after the crash involving its air force, marked Tuesday as a national day of mourning, with the national flag flying at half-staff across the country.

“It’s like this building was turned into a death trap. It was horrible, totally horrible,” said Sheik Rameen, 21, a student at the high school.