The 39 people, including a teenager, who were found in a refrigerated container in Essex yesterday are believed to be Chinese nationals.
The lorry, which arrived at Purfleet Docks early yesterday morning, came across from Belgium and was registered in Bulgaria.
Speaking on the Today Programme, Shaun Sawyer, Chief Constable for Devon and Cornwall Police, said the event was a “somber” moment.
Investigations continue into how the victims came to be found dead in an industrial estate in Grays.
Police moved the lorry to Tilbury Docks in order for the bodies to be removed with respect and identified.
The driver, named as Mo Robinson from County Armagh, has been arrested by Essex Police on suspicion of murder.
The Bulgarian-registered lorry arrived in Purfleet early yesterday morning. Within hours of it being in the UK, ambulance services were called and paramedics found the bodies in the truck.
Sawyer emphasised the push factors, which lead migrants to leave their countries, including war and famine.
He added: “There are very many, many thousands of people seeking to come here and resources do the best they can.
“The reality is that it’s incumbent on all of us to realise that there is the right and obligation to defend its borders.”
The arrival of the lorry raises questions as to how the UK can work to prevent further deaths from people smuggling.
The Calais-Dover crossing has high levels of security, which experts believe is pushing people smugglers to use other ports, such as Zeebrugge.
Sawyer emphasised the difficulty for the UK defending its borders when it’s an island have permeable borders, but “there will be tragedies until we resolve issues in countries as much as in the United Kingdom”.
Questions are now being asked how the supposedly Chinese nationals came to be in the container as well as how security can be improved.
At PMQs yesterday, MPs spoke of their horror at the event, including Jeremy Corbyn, who said: