At least 31 people were killed and 78 were injured when a Bangladeshi air force jet crashed on a school in the capital Dhaka on Monday, officials said.

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.

The fighter jet — a Chinese-built F-7 BGI — had taken off 12 minutes earlier from a military air base less than two miles from the school.