At least 20 people have died and five are listed as missing after a cargo ship caught fire while moored in the Chinese port of Qingdao. There were 42 people on board in total - twelve were evacuated safely.

Twenty dead and five missing out of forty-two. That is half a crew and half a work shift, in one afternoon, on a ship that was not sailing at all.

According to a photograph published by the state agency Xinhua, the ship was identified as the "Ocean Melody", sailing under a Liberian flag, data from the publicly available vessel tracking site VesselFinder shows.

The ship was under repair

That is the key detail: the vessel was not at sea but undergoing repairs at the Beihai Shipbuilding yard in Qingdao, one of the largest maritime hubs on China's north-eastern coast.

A ship under repair means people inside working, not a crew on deck under way. That also explains the number: forty-two on a moored ship is far more than an ordinary crew. What exactly started the fire is for the investigation to establish.

Chinese President Xi Jinping issued "important instructions" for the urgent execution of the rescue operation for the missing. The competent authorities are still assessing the scale of the incident and the extent of the damage.

Liberian flag, Chinese shipyard

What rarely makes the headlines is the registration. Liberia is one of the world's largest "flags of convenience" - a country under whose flag thousands of ships sail that have never seen a Liberian port, because that registration means cheaper taxes and looser obligations towards the crew.

When a ship like that burns in a third country, the question of who is accountable becomes a maze: the owner is in one jurisdiction, the flag in another, the shipyard in a third, and the crew - usually from a fourth. The investigation will show who skipped the safety procedures. The question is whether such a finding will ever reach anybody who can be held to account.

Twenty families are waiting for information today. Five are waiting for something harder still - for the number to close.