Police have confirmed that the 39 individuals found dead in the back of a lorry in Essex were all Chinese nationals.
Eight of the bodies discovered in the refrigerated lorry trailer were women, and 31 were men.
The victims had frozen to death in the vehicle, it has emerged.
Police continue to question a 25-year-old man on suspicion of murder after they carried out searches at two addresses in County Armagh in Northen Ireland, believed to be in connection with the lorry driver.
Investigators said "early indications" suggest one of the victims was a teenager.
Essex Police have launched a murder investigation, which they said they expect to be "lengthy".
Home Secretary Priti Patel tweeted: "This morning I met officers from Essex Police to express my thanks for their response to the tragic incident in Grays & receive an update on the investigation.
"I stand behind them as they continue their work to establish how this horrific event came to happen."#
The lorry is believed to have arrived in Purfleet in Essex from the Belgian village of Zeebrugge.
The vehicle was registered in Bulgaria under the name of a company "owned by an Irish citizen", according to Bulgaria's ministry of foreign affairs.
The front part of the truck, to which the trailer was attached, came from Northern Ireland.