More Vietnamese families came forward Saturday with information that their relatives may be among the 39 people found dead in the back of a container truck in southeastern England.

Police are questioning four people in connection with the tragedy as they grappled with one of the worst cases of people smuggling. Seeking to treat the victims with dignity, they have been slowly moving the bodies of the dead to a hospital mortuary, hoping to give the dead names.

But the task is proving difficult. People smugglers take the passports of their passengers to obscure their identities, stripping them of their names and giving them new documents when they arrive at their destinations.

Police in Britain initially believed that the victims were Chinese, but later acknowledged the picture was evolving.

Desperate families have been reaching out to the media, to local organizations and to acquaintances in Britain, hoping for any scrap of news.

A representative for VietHome, which serves Vietnamese people in the U.K., said it sent the pictures of nearly 20 people reported missing to the police.

In the village of Yen Thanh in north-central Vietnam, the mother and a sister of Bui Thi Nhung mourned as they set up an altar for the 19-year old woman. A family friend in the U.K. told them the horrible news of the migrant deaths.

Nhung paid an agent thousands of dollars in hopes of finding work at a nail parlour in Britain.

“Many families in Yen Thanh got rich from money sent back by their children working abroad,” said Le Dinh Tuan, a neighbour who had gone to her house to check on her mother.

Son feared among the dead

The father of 20-year-old Nguyen Dinh Luong feared his son was among the dead.

He told The Associated Press he had not been able to reach his son since last week, when the young man told his father he planned to join a group in Paris that was trying to reach Britain.

“He often called home but I haven’t been able to reach him since the last time we talked last week,” Nguyen Dinh Gia said. “I told him that he could go to anywhere he wants as long as it’s safe. He shouldn’t be worried about money, I’ll take care of it.”

Police forensics officers work on the truck, found to be containing 39 bodies, in Grays, east of London. (Ben Stansall/AFP via Getty Images)

He said his son left home in central Ha Tinh province to work in Russia in 2017, then went on to Ukraine. In April 2018, he arrived in Germany then travelled to France. He told his family that he wanted to go to the U.K.

Luong’s older brother, Pham Dinh Hai, said that Luong had a tattoo of praying hands on a cross on his right shoulder. The family said they shared the information with local authorities.

Woman, 26, sent text to family

The BBC reported it had been in contact with six Vietnamese families who feared their relatives were among the victims. Relatives of 26-year-old Pham Tra My told the broadcaster they had been unable to contact her since receiving a text Tuesday night saying she was suffocating.

“I’m so sorry mom and dad. … My journey abroad doesn’t succeed,” she wrote. “Mom, I love you and dad very much. I’m dying because I can’t breathe …. Mom, I’m so sorry.”

Formally identifying the victims is complicated by the very nature of people smuggling. Bernie Gravett, a former Metropolitan Police officer who now advises the European Union on human trafficking, told the BBC that the use of false identification and the sheer numbers of people traveling to Europe complicate such efforts.

“It’s a cruel stage for the families, because hundreds if not thousands are currently on those routes, so I appreciate we are getting calls from Vietnam saying my loved one is missing and my loved one may be on that lorry [truck] but they could be on another lorry,” he said.

Gravett said people smugglers normally give migrants fake documents depending on their country of destination.

“Most often they are stripped of all documentation so that when they get to the U.K. then documents are provided relating to this country.”

All of the victims’ bodies have been recovered and are undergoing post-mortems, Martin Passmore, detective chief inspector with Essex police said on Saturday. Efforts to identify all of them may be difficult if relatives avoid coming forward because they are in the U.K. illegally, he said.

Chinese seeking information

“We hope the British side can verify the victims’ identities as soon as possible,” said Tong Xuejun, a Chinese consular official in London said. “What I want to stress is that no matter what their nationalities are, this incident is a huge tragedy which arouses attention of the international community to issues of illegal immigration.”

Chinese Foreign Ministry spokeswoman Hua Chunying said Chinese authorities were also seeking information from police in Belgium, since the shipping container in which the bodies were found was sent to England from the Belgian port of Zeebrugge.

A man has been arrested after officials found a truck containing 39 bodies in Essex, England. Authorities say it’s believed the truck had travelled to the U.K. from Bulgaria. 1:57

British police believe the truck and container took separate journeys before ending up at the industrial park. They say the container travelled by ferry from Zeebrugge to Purfleet, England, where it arrived early Wednesday and was picked up by the truck driver and driven the few kilometres to Grays.

The truck cab, which is registered in Bulgaria to a company owned by an Irish woman, is believed to have travelled from Northern Ireland to Dublin, where it was loaded onto a ferry to Wales. From there it was driven across Britain to pick up the container.

Syrian reminded of his own escape

Syrian refugee Ahmad Al-Rashid knows what it was like for those who were trapped in the back of the truck because he survived a similar situation when a planned trip across the English Channel turned into hours of terror in 2015.

Al-Rahid, now 29 and living in Derby, Britain, had found himself gasping for breath inside a refrigerated shipping container with a group of migrants and a load of frozen chicken.

The truck hadn’t even left the French port of Calais when someone heard the cries of the desperate migrants and opened the doors.

“I was in their shoes. I knew the desperation of their last moments,” he said of the people who died this week. “In my case, someone came to help me. [For them] all their screams were in vain.”

Groups of migrants have repeatedly landed on British shores using small boats to make the risky Channel crossing, and migrants are sometimes found in the back of cars and trucks that disembark from the massive ferries that link France and England.

But Wednesday’s macabre find in an industrial park was a reminder that criminal gangs are still profiting from large-scale trafficking.

The tragedy recalls the deaths of 58 Chinese migrants who suffocated in a truck in Dover in 2000 after a perilous, months-long journey from China’s southern Fujian province. They were found stowed with a cargo of tomatoes after a ferry ride from Zeebrugge, the same Belgian port featured in the latest tragedy.

In February 2004, 21 Chinese migrants — also from Fujian — who were working as cockle-pickers in Britain drowned when they were caught by treacherous tides in Morecambe Bay in northwest England.