After nearly four years of relentless conflict in Yemen, the world has grown used to images of war, killing and destruction.

The United Nations estimates that since March 2015, around 6,600 Yemeni civilians have been killed, 10,500 injured - and the largest humanitarian crisis in the world, including famine and widespread disease, has been allowed to develop.

There's a danger rolling news coverage can make viewers de-sensitised to prolonged conflict, especially to the human suffering. But sometimes, a single event can make the world sit up and take notice.

A bombing on August 9, 2018, in the northern Yemeni city of Saada, near the border with Saudi Arabia, was one such event. 

Yemen is one of the poorest countries in the world.

In 2011, a revolution, part of the so-called Arab Spring, overthrew President Ali Abdullah Saleh.

The armed group in the north of Yemen, the Houthis, took advantage of the instability. They moved south and ultimately captured the capital, Sanaa, seizing power from the government of new President Abd Rabbu Mansour Hadi.

This Houthi takeover prompted a group of Arab states - led by Saudi Arabia and including the United Arab Emirates - to launch an all-out attack on Houthi positions in March 2015, saying that the Houthis were supported by Iran.

In August 2018, an international news story circulated, saying that coalition forces had hit a bus carrying children on a summer school excursion in Saada, close to the Saudi border.

"Saudi forces bombed a school bus. It managed to shock a lot of people. This is a school bus. This is not a military target," said Andrew Smith, spokesman for Campaign Against Arms Trade.

Fifty-one people, including 40 children, were killed and 77 others injured in the Saada attack.

The International Red Cross said their medical team at the al-Talh hospital there received the bodies of 29 children, all aged under 15. The hospital also treated 48 injured patients of whom 30 were children.

The Saada bus bombing triggered international condemnation, and the UN Security Council called for a credible and transparent investigation into the incident.

This film looks at what happened that day and how planes deployed by the Saudi-UAE coalition managed to bomb a bus full of Yemeni school children in Saada, killing nearly everyone on board.