How did they die?

That is unknown at this point.

If the container unit was turned on, the people inside could have frozen to death, because the unit could reach temperatures as low as minus 13 Fahrenheit. If the unit was turned off, they could have suffocated, because there would have been no ventilation.

And there may be other factors that investigators have not found or revealed.

Are there any suspects?

So far there is one: The driver of the truck, a 25-year-old man from Northern Ireland, remains in custody after being arrested on suspicion of murder.

The police have declined to identify him, but elected officials and the British news media have said he is Morris Robinson, who also goes by the name Mo.