Most of the 39 people found dead in the back of a truck near London were likely from Vietnam, a local priest from the rural, rice-growing community where many of the victims are believed to have come from said Saturday.
The bodies were discovered on Wednesday after emergency services were alerted to people in a truck container on an industrial site in Grays, about 32 km (20 miles) east of central London.
Police said initially they believed the dead were Chinese but Beijing said the nationalities had not yet been confirmed. Chinese and Vietnamese officials are now both working closely with British police, the two countries' embassies have said.
Maurice Robinson, the driver of the truck, has been charged with 39 counts of manslaughter and conspiracy to traffic people.
Police said the 25-year-old driver is due to appear at Chelmsford Magistrates Court on Monday. He was the first of those arrested to be charged in what is seen as one of the country's biggest cases of people smuggling.
Four others have been arrested in the case. U.K. police are struggling to identify the victims, who are believed to have come from Asia, and autopsies are being performed. The Vietnamese Embassy in London has set up a hotline for families to call about missing family members.
Father Anthony Dang Huu Nam, a Catholic priest in the remote town of Yen Thanh in northern-central Vietnam's Nghe An province, 300 km (180 miles) south of Hanoi, told Reuters he was liaising with family members of the victims.
"The whole district is covered in sorrow," Nam said, as prayers for the dead rang out over loudspeakers throughout the misty, rain-soaked town on Saturday.
"This is a catastrophe for our community."
On Saturday evening, Nam led around 500 worshippers in prayers for the dead as they held lit candles in the modest, white-walled church in Yen Thanh.
"We are here to pray for justice and peace, and for the victims of society. We pray for the 39 people who lost their lives on the way to the U.K.
They are people coming from central Vietnam, our land," Nam said. Nam said families told him they knew relatives were traveling to Britain at the time the container truck was been traveling and had been unable to contact their loved ones.
Vietnam's Prime Minister Nguyen Xuan Phuc ordered government officials to help establish the identities of the victims and look into cases of Vietnamese citizens sent abroad illegally. British police declined to elaborate on why they first identified the dead as Chinese and said they would not give more details about the identities or nationalities of the victims until the formal identification process had taken place.