Hundreds of students are protesting near the site of the crash of a Bangladesh air force training jet into a school in the nation’s capital, demanding accountability, compensation for victims' families and the halt of training flights.

The death toll from the crash rose to 31 on Tuesday, including 25 students, a teacher who died from burn injuries she sustained while helping others get out of the burning building, and the pilot of the training aircraft.

Firefighters further secured the scene of the crash in Dhaka’s densely-populated Uttara neighborhood while an investigation by the military was ongoing. The country’s civil aviation authority was not involved in the investigation directly.

The F-7 BGI aircraft crashed soon after it took off at 1:06pm on Monday from the airbase in Kurmitola in the capital on a routine training mission. The military said the plane experienced a mechanical failure.

Sayedur Rahman, special assistant to the chief adviser on health, told reporters that 27 people had died and 88 were admitted to hospital with burn injuries. The toll has since risen.

The government announced a day of mourning, with flags at half-mast and special prayers at all places of worship.

The students protesting outside the crash site at the Milestone School and College Tuesday demanded “accurate” publication of identities of the dead and injured, compensation for the families, and an immediate halt to the use of “outdated and unsafe” training aircraft by the Bangladesh air force.

The pilot was among those killed in the incident, the military said, adding that a committee had been formed to investigate what happened.

The F-7  BGI is the final and most advanced variant in China's Chengdu J-7/F-7 aircraft family, according to Jane's Information Group. Bangladesh signed a contract for 16 aircraft in 2011 and deliveries were completed by 2013.

Firemen work at the site of the crash in Dhaka. – AP

The crash comes weeks after an Air India plane crashed into a medical college hostel in Ahmedabad in neighbouring India, killing 241 of the 242 people on board and 19 on the ground in the world's worst aviation disaster in a decade.

Flight Lieutenant Md. Toukir Islam, made “every effort to divert the aircraft away from densely populated areas toward a more sparsely inhabited location," the military said. “Unfortunately, the aircraft crashed into a two-storey building” within the school.

It is the deadliest airplane crash in the Bangladeshi capital in recent memory.

Local media indicated most of the injured were students. Relatives panicked at the scene as rescuers, using tricycle rickshaws or whatever was available, transported the injured to local hospitals.

A desperate scene unfolded as the crash occurred.

Local residents and rescuers carried wounded students on their laps, while worried parents ran frantically. One father sprinted with his daughter cradled in his arms. A mother cried out, having found her younger child, but desperately searching for her elder. Students said the school’s buildings trembled violently followed by a big explosion, sending them running for safety.

Screams and desperation filled the air at a nearby hospital.

Women at the site of the crash in Dhaka. – Reuters

Doctors at Uttara Adhunik Hospital reported that more than 60 students, many aged 12-16, were transferred to a specialised burn hospital after arriving with burn injuries.

At the crash scene, soldiers used megaphones to control the crowd, complicated by the area’s dense population, a nearby metro station and numerous surrounding shops and homes.

By the evening, rescuers continued to scour the debris, searching for bodies.

Bangladesh’s interim leader Muhammad Yunus pledged an investigation into the crash, expressing his deep sorrow over the “heartbreaking accident” at Milestone School and College.

In a statement, he lamented the “irreparable” loss suffered by “Air Force personnel, students, parents, teachers, staff, and others”, calling it “a moment of deep national grief”.

Indian Prime Minister Narendra Modi expressed shock and sadness over the “tragic air crash in Dhaka” that resulted in the loss of many lives, including young students.

“Our hearts go out to the bereaved families,” Modi said in a post online. “India stands in solidarity with Bangladesh and is ready to extend all possible support and assistance.”

Rafiqa Taha, a student who was not present at the time of the crash, said the school, with some 2000 students, offers classes from elementary to twelfth grade.

“I was terrified watching videos on TV,” the 16-year-old said. “It’s my school.”