The known facts about how 39 people died in a lorry in Essex this week remain sparse, stark and shocking. The 31 male and eight female victims were all adults and, it became clear on Thursday, all were Chinese nationals. They arrived in Britain from Belgium by sea, in a refrigerated container, shortly after midnight on Wednesday morning. The container was then attached to the back of a lorry that had come from Northern Ireland via Holyhead and was driven to an industrial estate in Essex, where it was discovered about an hour later. There were no survivors.

Fundamental parts of the story remain unclear and are under active investigation. The most important of these is to discover who the victims were and to tell their stories. Did they enter the container willingly or under duress? Who was responsible for loading them into the container? By what route did they reach Essex? Were they being trafficked or were they migrants entering the country illegally? Answers to all these questions are essential. For this appears to amount to mass murder.

It is not, however, the first case of its kind. Nor is it in any way unique. People-smuggling is now an integral part of the new global economy. According to the International Organization for Migration’s missing migrants project, more than 4,000 people have died or gone missing on migratory routes around the globe for each of the last five years. There have also been very similar tragedies to this one before. In 2000, 58 Chinese people were found dead in Dover in a truck that had travelled, like the one this week, from Zeebrugge in Belgium. They had died of suffocation after the container’s only air vent had been closed to lessen the chance of detection. In 2014, 35 men, women and children were discovered near to death in a container at Tilbury. This week’s deaths come in spite of better detection methods and greater official alertness. Many drivers are more thoroughly trained to conduct regular walk-around checks to detect tampering. But improvements at ports like Calais may have diverted people-smugglers to less tightly monitored ports such as Zeebrugge. The use of refrigerated containers, unimaginable though this is in human terms, may be being risked because the containers are more effectively sealed from scrutiny.

Better detection technology and adequate levels of personnel are certainly important. So is effective punishment for the people-traffickers and smugglers. But global migration will not be controlled merely by raising the drawbridge at the white cliffs of Dover. This is an international problem. It requires international action. It also requires some appreciation of the modern migratory pressures which are forcing and encouraging millions to make long and dangerous journeys to escape suffering and poverty and to seek safer and better lives in countries like Britain. If a policy of blocking the borders means people are prepared to clamber into refrigerated containers to get across that border, then the policy itself may be part of the problem.

The shock that the discovery of the 39 bodies has created across Britain is palpable. No one can be comfortable that such inhuman acts are taking place in our midst, alongside normal life. The impact on the emergency services, on the workforce on the industrial estate, and on local communities, is particularly deep. But it is not enough simply to say that such treatment of human beings is intolerable. All of us, and all our governments, must ask if we also bear some responsibility for the fact that Britain became the final resting place for a lorry filled with corpses.