Tilbury Docks container stowaways 'Sikhs from Afghanistan' 17 August 2014 Last updated at 09:56 ET Police at Tilbury Docks on August 16 They were discovered after a freighter arrived at Tilbury Docks from Belgium on Saturday and have been described as victims of "people trafficking". One man was found dead and the others were taken to hospital to be treated for severe dehydration and hypothermia. Thirty have now been released into the care of police and Border Force staff. They are to be interviewed to find out how they came to be inside the container. Police launched a homicide investigation following the man's death and officers are working with Interpol and other international authorities to try to establish what happened. A post-mortem examination is being carried out on Sunday and the container is being forensically examined. 'Horrific ordeal' Four remain at Southend Hospital. It is thought they will be discharged later on Sunday. 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." The Red Cross provided food and welfare for the group overnight. Norstream (library image) The freighter Norstream left Zeebrugge on Friday evening The discovery was made after the container arrived from the Belgian village of Zeebrugge at about 06:00 BST on Saturday when "screaming and banging" were heard coming from inside. All the remaining containers on the ship have been searched and no-one else has been found. Essex Police said there were initial concerns more people could be inside a container that arrived at Purfleet but that this turned out not to be the case. Belgian police said they believed the lorry which delivered the container in Zeebrugge had been identified through CCTV footage. Chief Inspector Peter De Waele said it was likely the people were already inside the container when it was dropped at Zeebrugge as it appeared "impossible" the group could have entered it during the hour it was at the port. It is not known where the container, one of 64 aboard the P&O commercial vessel Norstream, originated, nor where the people inside it were heading. 'Exploited by gangs' Former head of the UK Border Force Tony Smith said those inside the container were victims of international organised criminals. He told the BBC: "They're being exploited because the prize is a passage to the West - that's what they want, they want to migrate to the UK or to Europe but they're being exploited by criminal gangs who are probably taking their entire life savings away on the promise of a passage to the West. "We really need to get a message out to migrants that if they want to come to this country there are legal routes that they need to explore and they need to apply for visas and permits." Anthony Steen, chairman of the Human Trafficking Foundation, said: "It shows how desperate people are to improve their economic situation - how desperate they are to leave their own homes, and own countries, and hope to arrive in somewhere that's more accommodating, more kind, and offering them a better quality of life. Usually, they're sadly wrong." Police have set up a "casualty bureau" hotline for anyone concerned about relatives. The numbers are 0800 056 0944 or 0207 158 0010 if dialling from outside the UK. http://www.bbc.com/news/uk-28827133#"