Police in southeast England say emergency services have recovered 39 bodies from a container truck believed to have been driven from Bulgaria.
Chief Superintendent, Andrew Mariner, said on Wednesday that authorities were in the process of trying to identify the deceased; 38 adults and one teenager.
Police were alerted by the ambulance service shortly before 1:40am local time (00:40GMT) following the discovery of a truck container with people inside at the Waterglade Industrial Park, which houses mostly courier and logistics companies.
Mariner said the truck entered the country on October 19 and that police were “working closely with our partners to investigate”.
The 25-year-old driver, from Northern Ireland, was arrested on suspicion of murder, the police said.
UK Prime Minister, Boris Johnson, said he was “appalled by this tragic incident”.
“I am receiving regular updates from the Home Office and will work closely with Essex Police as we establish exactly what has happened,” he said. “My thoughts are with all those who lost their lives and their loved ones.”
Al Jazeera reports that the lorry entered the UK mainland at the port of Holyhead in North Wales, which is “the transit point for freights and lorries coming in from Northern Ireland”.
“A murder inquiry has begun,” he added, “but everybody’s thoughts will be with the bereaved relatives of the deceased.”
Essex Police said the people were pronounced dead at the scene in Grays, east of London. “This is a tragic incident where a large number of people have lost their lives,” the service said in a statement.
A cordon has been put in place and access to and from the Waterglade Industrial Park remains closed.
“The cordon around the scene is expected to be in place for quite some time,” Brennan said.
“The police are saying it will take a lengthy time to identify the victims,” he added.
Bulgarian authorities said they could not yet confirm that the truck had started its journey from Bulgaria.
“We are in contact with our embassy in London and with British authorities,” foreign ministry spokeswoman Tsvetlana Krasteva said.
Essex Police appealed for anyone with any information about the lorry’s route to get in touch via their website.
“The identification of victims remains our top priority,” said Pippa Mills, Essex Police’s deputy chief constable.
Jackie Doyle-Price, the local Conservative MP, said “people trafficking is a vile and dangerous business”, adding: “Let’s hope they bring these murderers to justice.”
Haulage industry experts suggested the lorry was likely to have arrived in Ireland from Cherbourg or Roscoff in France, avoiding the tighter checks for people-smuggling at Calais and Dover.