British police have said that all 39 people who were found dead in a truck in a UK industrial park on Wednesday were Chinese nationals.
"We have since confirmed that eight of the deceased are women and 31 are men and all are believed to be Chinese nationals," Essex Police wrote in a statement.
Their cause of death has yet to be established, the police added, as they "must undergo a full coroner's process ... before we move on to attempting to identify each individual within the trailer. This will be a substantial operation and, at this stage, we cannot estimate how long these procedures will take."
On Wednesday, 25-year-old Northern Irish truck driver, Morris Robinson, was arrested on suspicion of murder after a truck, originating from Northern Ireland, and a container with the victims were found at an industrial park in Grays, Essex, a town 20 miles east of London.
CNN witnessed Northern Ireland forces search two properties in County Armagh, southwest of Belfast. Local residents identified one of the properties as the home of Robinson's parents.
As the horrifying series of events unfolded, Members of Parliament speculated in the House of Commons that the incident was linked to human trafficking -- a claim yet to be confirmed by the police.
Police in England, Northern Ireland and now Belgium scrambled overnight to establish the chain of events that led to the deaths.
CNN witnessed Northern Ireland forces search two properties in County Armagh, southwest of Belfast. Local residents identified one of the properties as the home of Robinson's parents.
They also told CNN that Robinson's parents have traveled to England to support him.
Essex Police said Wednesday that the container arrived at a nearby town, on the River Thames, after traveling from the Belgian port city of Zeebrugge. It was then transported by a red Scania truck to Waterglade Industrial Park.
Belgian officials said Thursday that an investigation focusing on the "organizers of and all other parties involved in this transport," adding that the container arrived at Zeebrugge on Tuesday afternoon at 2.49 p.m CEST and left the port the same day.
The container arrived in Purfleet, a town on the River Thames, early Wednesday morning, the Belgian Federal Public Prosecutor's Office said in a statement.
"It is not yet clear when the victims were placed in the container and whether this happened in Belgium," it said.
The truck was found on a street at the heart of the usually busy industrial area. Police -- who were called to the scene at around 1:40 a.m. on Wednesday -- said the victims were found dead on the scene.
Road haulage experts said the truck appeared to be refrigerated. That could mean freezing temperatures of anywhere between -5 to -10 degrees Fahrenheit (-20C to -23C), Richard Burnett, chief executive of trade body the Road Haulage Association, told PA news agency, making conditions "absolutely horrendous" for anyone stuck inside.
"I can't overstate how big a tragedy it is that 39 people felt like they had no better option than to get in the back of this truck and obviously it's ended in an absolute tragedy," Matthew Carter, an emergency communications delegate for the British Red Cross, told CNN at the scene on Wednesday.
He added that the charity was also giving support to the forensic team, offering them "somewhere where they can come and reflect, have a chat."
"It's not something (emergency services) deal with on a day-to-day basis," Carter told CNN. "One chap told a colleague of mine that it's the hardest thing that he's dealt with in (his) 30-year-career."
The truck was later moved, as seen by CNN, to a "secure location" at Tilbury Docks, about a 20-minute drive away from Grays, to "maintain the dignity of those who have lost their lives."
