Hundreds of students gathered outside the smoldering remains of a school in the Bangladeshi capital on Tuesday to demand answers after a military jet slammed into the campus, killing dozens of children.

The Chinese-made F-7 BGI training aircraft experienced a ’technical malfunction’ moments after takeoff from the A.K. Khandaker air force base at 1:06 p.m. Monday, according to a statement from the mil

At least 20 deaths have been reported so far. And over 170 people have encountered injuries, according to officials.

A Bangladesh air force training jet has crashed into a school campus, killing at least 19 people. Here’s the latest we know: “Bangladesh Air Force’s F-7 BGI training aircraft crashed in Uttara. The aircraft took off at 13:06 [07:06 GMT],” the Bangladesh military’s public relations team said.

The F-7 BGI is a fighter jet that China specially made for Bangladesh. It replaced the older models in the Bangladesh Air Force, like the F-7M and F-7MB. Apart from Bangladesh, other countries such as Myanmar, Nigeria, Iran, Egypt, Zambia, and Sudan also use this aircraft.