13 children among container group
Thirteen children aged as young as one were among the Afghan immigrants rescued from a shipping container yesterday.
Thirty of the 35-strong group found screaming and banging at the Port of Tilbury are being quizzed by officials after being released from hospital.
Essex Police said they include nine men and eight women aged between 18 and 72 as well as 13 children aged between one and 12.
It was also revealed that the man found dead inside after the container was opened - prompting a homicide investigation - is believed to have been in his 40s.
A post-mortem examination was carried out today but further tests are set to be undertaken to establish the cause of death.
Four others remain in Southend Hospital and are expected to be kept in for a second night.
A statement issued by police said the 30 people who have been released from hospital after being treated for hypothermia and dehydration are still being spoken to "about their ordeal".
Once the interviews have been completed, they will be passed into the care of the Border Force.
It was disclosed earlier that the immigrants are Sikhs who are understood to be from Afghanistan.
Superintendent Trevor Roe, of Essex Police, said: "The welfare and health of the people is our priority at this stage.
"Now they are well enough, our officers and colleagues from the Border Force will be speaking to them via interpreters so we can piece together what happened and how they came to be in the container.
"We now understand that they are from Afghanistan and are of the Sikh faith.
"We have had a good deal of help from partners within the local Sikh community in the Tilbury area to ensure that these poor people, who would have been through a horrific ordeal, are supported in terms of their religious and clothing needs."
A post-mortem examination into the man's death is being conducted today while the container in question is being forensically examined.
Police believe substances found in the container are cleaning chemicals which are not thought to pose any health risk.
The port has resumed business as usual while police said concerns that a further container with people inside may have arrived at Purfleet were later dismissed.
The company which owns the container has not been named.
Belgian police earlier indicated that they believe the immigrants were probably already inside when it was dropped at a European port before setting sail for Britain.
Peter De Waele, spokesman for the Federal Police in Belgium, said it appeared to be "impossible" for the 35 men, women and children to be loaded into the unit in the time it was at Zeebrugge, a port in the north of the country.
He said investigators have been combing CCTV and are "very hopeful" that they can track down the driver and company of the vehicle that deposited the container.
Mr De Waele told the Press Association each container is captured on camera and their seals are subject to "very strict" controls.
He said: "We saw that this container was there for one hour in all in an area where there is a lot of cameras, a lot of people and a lot of cars driving. It was around 6pm, so it wasn't dark.
"We think that the possibility (is that) the victims were already on the container before it was put down in Zeebrugge because in that area it is rather impossible to put 35 people in that container.
"That is not exact information. I think the investigation has to give answers to this question."
He declined to confirm whether detectives have already identified the vehicle which delivered the container to Zeebrugge.
But he added: "My colleagues told me that they were very hopeful looking at the pictures that they (could) find the company and also the driver who put the container in Zeebrugge.
"It is too early saying the driver is involved but when we find the driver we can work backwards."
Mr De Waele added that they are working closely with Essex police and described tackling human trafficking as a "priority" in Belgium.
The container was one of around 50 on board the P&O Ferries commercial vessel the Norstream when it arrived in Essex.
The immigrants were rescued after port authorities heard noises from inside at around 6.30am yesterday.
Bhai Amrik Singh, chair of the Sikh Federation (UK), said: "It is a disgrace the persecution of the tiny minority of Sikhs from Afghanistan has largely been ignored and it takes an incident like this to remind us all that they are also being exploited by human traffickers."
Nick Alston, Police and Crime Commissioner for Essex, said: "The death of the man in a container found at Tilbury on Saturday was a shocking incident. One person died and many others might very easily have done so."
He said the developments should "highlight for us the evil of the abuse and exploitation of vulnerable", adding: "The police and partner agencies are continuing to investigate the circumstances of those found in that container.
"But we can be sure that almost all cases of human trafficking involve exploitation by callous organised criminal gangs."
Footage obtained by ITV News apparently shows members of the group after they were released from the container.
The clip shows some of the migrants sat on the floor while the sound of wailing and shouting can be heard.