Bangladesh is observing a day of mourning after at least 27 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.

The armed forces said that the jet had reportedly experienced a mechanical fault after taking off for a training exercise, with the pilot being among those killed, adding that an investigation would be held.

The crash marks the deadliest aviation disaster the country has seen in decades, and while details are still emerging, here’s what we know about the crash so far.

The training aircraft had taken off from a Bangladesh Air Force Base in Dhaka at just after 13:06 local time (07:06 GMT) and crashed soon after in the Uttara neighbourhood.

The air force said in a statement that the F-7 jet had suffered a mechanical fault and the pilot, Flight Lieutenant Md. Taukir Islam, had tried to steer it to a less crowded area. He was among those killed.

A teacher at the college, Rezaul Islam, told BBC Bangla that he saw the plane “directly” hit the building.

Another teacher, Masud Tarik, told Reuters that he heard an explosion: “When I looked back, I only saw fire and smoke… There were many guardians and kids here.”

Images from the scene in the hours after the crash showed scores of emergency service workers sorting through charred rubble in a bid to find survivors.

An investigation committee has been formed to look into the incident, said the armed forces in a statement.

Most of the victims were enrolled at the Milestone School and College, a private institution with around 2,000 students, from pre-school to senior secondary levels.

At least 17 of the deceased are children, the health ministry said on Monday.

Year 10 student Farhan Hasan told BBC Bangla he had just left the building after finishing an exam when he saw the plane crash into the building.

“My best friend, the one I was in the exam hall with, he died right in front of my eyes,” he said.

“And many parents were standing inside because the younger kids were coming out since it was the end of the school day… the plane took the parents along with it.”

One man’s eight-year-old nephew was among the students who died in the crash. “My beloved nephew is in the morgue right now,” he said, his hand resting on the arm of his younger brother, the boy’s father, who kept repeating: “Where is my son?”

A teacher told the Dhaka Tribune that classes for grades five to seven were being held in the building where the plane crashed.

“Although classes ended around 13:00, many students were waiting for private coaching,” the teacher said.

At least 170 people were injured with an on-duty doctor at the Uttara Adhunik Medical College Hospital saying most of the injured were aged between 10 and 15 years old, many suffering from jet fuel burns.

More than 50 people were taken to hospital with burns, many in critical condition, said a doctor at the National Institute of Burn and Plastic Surgery.

Plane crashes are relatively rare in Bangladesh.

The last time it saw a major plane disaster was in 1984, when all 49 people aboard a Biman flight – Bangladesh’s national flag carrier – died after the plane crashed into a marsh while landing near the airport in Dhaka.

In 2018, a US-Bangla Airlines flight crashed while trying to land at an airport in Kathmandu, Nepal, killing 51 people.

In 2008, another F-7 training jet crashed outside Dhaka, killing the pilot.

The city is still reeling from the mass casualty event, and medical efforts are underway.

The National Institute of Burn and Plastic Surgery was on Monday swarmed by family members trying to find their loved ones, as well as volunteers who queued up to donate blood to the injured. A number of politicians were also seen visiting victims at the hospital.

An emergency hotline has been launched to deal with casualties from the crash, Muhammad Yunus, leader of Bangladesh’s interim government, wrote on X.

Yunus said that the bodies of those who could be identified would be handed to their families, while the others would be identified through DNA testing.

He also urged the public to avoid unnecessarily crowding at hospitals to allow medical work to continue undisrupted.

“Necessary measures” would be taken to investigate the cause of the incident and “ensure all kinds of assistance”, he said.

An investigation committee has been set up to look into the incident, authorities have said.

The incident has drawn condolences from leaders of neighbouring countries, including Pakistani prime minister Shehbaz Sharif and Indian prime minister Narendra Modi.