Post-mortem examinations are due to be carried out on some of the 39 people found dead in a lorry in Essex.
On Thursday night, the first 11 victims were transported under police escort from the Port of Tilbury to Broomfield Hospital in Chelmsford.
“The next stages will be for post-mortems to be carried out,” Essex Police said in a statement.
However, the force warned that the investigation will take “some considerable time”.
It comes after the bodies of eight women and 31 men – all believed to have been Chinese nationals – were discovered in a refrigerated trailer on Wednesday.
The remaining bodies will be transported in stages, with police expecting all the victims to be moved to hospital by the end of the week.
The driver of the truck remains in custody on suspicion of murder. Detectives were granted more time to question the 25-year-old, who was named locally as Mo Robinson from Northern Ireland.
Essex Police Chief Constable Ben-Julian Harrington said he had the “utmost confidence” in his officers as the force leads its largest-ever murder investigation.
Irish police are conducting follow-up inquiries in relation to the registrations and movements of the refrigerated container and the Irish-owned truck.
Three addresses have been searched in Northern Ireland as part of the probe.
Councillor Paul Berry said the village of Laurelvale, where the Robinson family live, was in “complete shock”.
Irish company Global Trailer Rentals Ltd (GTR) confirmed it owned the refrigerated part of the lorry and a spokesman said the company was “shellshocked” and “gutted” by the news.
The firm said the trailer had been leased on October 15 from its rentals yard in Co Monaghan, in the Republic of Ireland, at a rate of 275 euro (£237) a week.
It said it provided police with information about the person and company that leased the trailer, as well as offering to make tracking data available.
The trailer arrived at Purfleet from Zeebrugge in Belgium at around 12.30am on Wednesday, and the front section to which it was attached, known as the tractor, came from Northern Ireland via Holyhead in North Wales on Sunday.
The lorry and trailer left the port at Purfleet shortly after 1.05am and officers were called to the Waterglade Industrial Park on Eastern Avenue in Grays at 1.40am.
Questions have been raised about when the victims entered the sealed refrigerated trailer, where temperatures can be as low as -25C, as well as the full route of the unit.
Vigils have been held in London and Belfast to pay tribute to the victims and a book of condolences has been opened in Grays.